kluge

I think one of the big factors that will come into that decision is whether or not the UA feels that they have a solution to the Russian air power. Back during Kherson it was said that the main thing that hurt and stopped the UA was Russian air. Granted we don't have a lot of information on that, but it was widely reported. So if it is a big factor, recent build up of airframes by the RuAF would point to them thinking that heavy air interdiction will be their card to stop any break throughs. 
If the UA is confident that they can provide an air denial bubble over any rampaging columns then I'd bet we see them try the break through and exploit option. If they aren't then the bet is on the corrosive/attritional approach. 

Most of that will be handled by the various S2 staffs of all levels.   S2 is the intel people.  Their job is to get a handle of understanding enemy intents and dispositions.  Armies operate according to doctrines and understanding your enemy's doctrine of how he uses and deploys his artillery assets gives you the ability to 'predict'  where and how he will deploy his artillery assets in a given area.   That is the start point of your intel gathering plan and where you deploy your drones, position your counter artillery radars, etc.    
It may seem like 'black box' stuff but a good S2 staff can seem like they are reading the mind of the enemy.   I have worked in the past as the BAIO (Brigade Artillery Intelligence Officer) in a Bde S2 shop and every exercise with opfor forces, I have been able to predict where they would deploy their artillery and I have been accurate to within 1.5 kilometers on my assessment and having some intel sensor / humint discover where the opfor guns were deployed with enough accuracy to counterbattery them.
1000 sqkm is not an issue for a real good and well trained S2 staff.  It might seem like 'black box' stuff but good S2 staff can nail down enemy locations and intents with a high degree of accuracy.
An edit just to clarify.  The 1000 sqkm is not one S2 staff.  A number of divisions and their subunits is responsible for that large an area.   There will a Corp S2, a number of Div S2s and numerous Bde S2s all talking with each other.  Each step down is more and more focused on a particular smaller parcel of ground.  Didn't want to give the impression that a single S2 shop is looking after 1000sqkm.  There is potentially dozens of S2 shops working that problem.

Just in time for the discussion over the past page or so, today's ISW post goes into detail on what RU units are committed in Ukraine, where they are located and the what shape they're in.
TLDR is they're not in great shape after months of relatively fruitless local actions and are going to have a hard time defending against a large mechanized offensive.
https://www.understandingwar.org/backgrounder/russian-offensive-campaign-assessment-april-23-2023

One could imagine something along the lines of a river crossing would be a quick way to create uneasiness about badly defended sectors.

This does assume that the RA can swing those guns to and from Close and General support quickly (building on your note #1)  Based on what we saw at Severodonetsk last summer RA fire planning seems pretty linear, which may lean more the way Steve added it up.  In fact I would bet good money that have plotted out rigid sector fire support that is pretty static compared to western doctrine.  RA C2 has not shone in this war, I have my doubts as to it somehow stepping out of the phone booth now. Of course the UA should help this along where they can.

If this is true then they have shifted forces dramatically into this area.  If we recall the intel leak on force density there was nowhere with greater than about 250 pers per km.  So in order to focus this force size the RA will have had to bleed off other areas of the line a LOT.  This is also a pretty dangerous concentration easily seen by the UA.  There must be other areas of the line that are basically abandoned.
So the RA clearly got the message on the “strategic land bridge”.  My bet is the UA will attack elsewhere to pull that density away and then attrit them as they try to relocate.

True, but speed of reaction and 'stickiness' of engagement matter. An artillery battalion can be engaging a target "over there" one minute, then switch to engaging a different target 25km away "over that'a way" literally 5 mins later, then back again 5 mins later, then to a third completely different location 5 mins after that.
Once you commit tanks or IFVs to a battle, they're pretty much stuck there for at least the rest of the day. You might be able to pull them out overnight and commit them to a different battle maybe 30-odd kms away tomorrow, but that's about the best you can hope for.
Perhaps. That doesn't make it sensible though For one thing, it undercounts what can be expected by 1 or 2 orders of magnitude, it ignores C2 freedoms and constraints, and ignores qualitative differences in equipment. By that I mean that say - for example - both sides have exactly the same number of guns - 160 guns to cover 160km of front. In that case they are 'evenly matched' at 1 gun per km. But suppose one side has yewbeut guns and extended range ammo, which gives them twice the range; 60km vs 30km. Both still have 1gun/km, but one side can expect to face 80 guns anywhere along the front, while the other will only be opposed by 40 - a 2:1 advantage.

That's kind of the wrong way to think about artillery, although I am making the perhaps heroic assumption that the Russians aren't just using their guns in direct-fire mode.
The D-30 ("artillery over 100mm") has an effective range of about 15 km, so if it was right on the front line each gun could - theoretically - cover 15km to the left and 15 km to the right, for 30km total coverage. But it won't be at the front, so call the effective coverage 20km per gun, therefore at a minimum about 7 positions are required to cover the entire lineage. There are 763 guns in total, so at any point along that frontage you can expect to be opposed but about 110 guns, or about 10 battalions.
Similarly for the MLRS. Those have highly variable ranges, but 30km seems about typical. That gives 60km of maximal frontline coverage or 40km of effective coverage, so 3 positions minimum across the 125km, with 70 launchers at each position.
So, an attack anywhere along that front can expect to be be opposed by 10 battalions of barrel artillery and 6 battalions of MLRS, along with a battalion of ballistic missiles messing around in your rear area. Not 6 guns and 2 MLRS launchers.
Note1: Command and control arrangements can upset that; commanders might not be willing or able to share "their" indirect fire-support assets across divisional or higher organisational boundaries.
Note2: the above rough calcs assume a perfectly straight front line. Any wiggles and salients (convex or concave) will increase the average density.

It's imagination that UKR "elite forces" involved on flanks (3rd and 5th assault brigades. 92nd mech. - at least one battalion, somewhere unit of 77th air-assault brigade was spotted), but inside the city just light infantry mostly (TD, border guards, Chechen battlion, rifle battalion of 93rd mech, some SOF etc) with some armor support of 93rd brigade. 

This. The point is to elicit a military reaction and force adjustment. It has already provoke nervous discussion on the Russian side.

I think crossing the river in force is probably just too hard. But if the Ukrainians are considerably stronger than I think, there are good paved roads from Kherson and Nova Kakhovka Straight to the choke points at the top of Crimea. If the Ukrainians could even credibly threaten along this axis, while also attacking towards Melitopol from the North, it could unhinge the entire western third of the land bridge . Of course if Ukraine strong enough to do this, then they are probably going to smash the Russians almost regardless of the plan.

They have been talking about this for years.  Beyond cooking one’s own soldiers in their own juices, its practical application on the battlefield is really limited.  SOF and elements of recon maybe, but large infantry units become unpractical very quickly and gain little advantage for the cost.  NVGs and radars still work to pick up large bodies of infantry and the logistics of keeping a bunch of soldiers in space suits is just crazy.
And it does nothing for the real targets of thermal, vehicles.

I've seen original tweet about this. In comments one soldier told this clothes doesn't prevent thermal spotting, but can blur figure outline from distance.
PS. it's good for not hot weather, when temperature will grow up to 20+ to move in this "thermos" will be a torture

not the 'evidence', but it also doesnt mean that it isnt true. RU doesnt make these kind of claims in a daily basis. 
the claim they made that UKR speciaal forces tried to take the nuclear power plant also turned out to be more true than some of us here expected.

The other thing strongly implied in todays ISW is that the ground is still bottomless bog, and we are therefore at least a week out from the Ukrainians kicking off for real.

Def Mon mentioned something about this a few days ago.
 

If only we had a good simulator to test some of these ideas in? Anybody have any leads?🤣

I agree with you and I am afraid that it is going far away from  the topic, but it reminds me of the Puerto Rico case as a short of American Crimea. When it was military conquered by the United States in 1898, there was almost no movement for independence. the island was politically calm, almost no Porto Ricans felt oppressed, and had had political representation in the Spanish parliament for almost a century (16 representatives from Puerto Rico and 30 from Cuba out of 401 representatives in the Spanish Parliament in 1898)  ( https://adelantereunificacionistas.com/2020/03/16/diputados-provincia-de-puerto-rico-1809-1898/ ). Puerto Rico remains today an Spanish-speaking country with more or less the same population mix they had in 1898. Less than 5% of the Porto Ricans speaks English as their main language, while 95% speaks Spanish. 
Thought things seem to move more to statehood (in 2020 52,5% of Puerto Ricans voted for statehood, but at the same time 47,5% voted against it), there are a small independence movement (AFAIK they have never been more than 5% of the population)  and there is even a small, residual group who defends integration in Spain as Spain's 18th "comunidad autónoma" (a comunidad autónoma is an autonomous region with their own government and parliament, not much different from and U.S. state or a German Land and obviously with full representation in the Spanish Congress and Senate) ( https://www.theguardian.com/world/2015/aug/30/puerto-rico-movement-pitches-solution-to-economic-woes-rejoin-spain )

Spain has never shown any interest in recovering the island or confront the US. but let's see an highly hypothetical scenario where Spain, this time with a very nationalist government, wants to recover past glories, and has strong political and military support from a more unified and aggressive EU who want to act in an independent way. The EU thinks that recovering Puerto Rico and getting a foothold in the Caribbean Sea is an strategic must and there is a window of opportunity for doing it, because the U.S. is in a persistent internal political crisis which makes USA politically and militarily weak for some time. Then they do cover moves for a decade or so that the States cannot counter. The hybrid action unfolds until a referendum is fully won in a legal and democratic way, so 75 or 80% of the Puerto Rico people vote to become an independent country in order to be free later to integrate in Spain and the EU. No need for the EU to send little green men.

In this case Puerto Rico plays Crimea, the United States plays Ukraine and the European Union plays the Russian Federation (a less military aggressive one, so there is no need for little green men)  

The questions for this absurd, crazy and highly hypothetical scenario would be:
The United States would accept the democratic decision of the Puerto Rican people? Would be OK for the U.S. that Puerto Rico became a part of the European Union?
AFAIK from an American point of view  and according to the Property Cause, it was the U.S. congress who should decide, no matter what Porto Ricans said and the EU wanted., so, would an American military intervention to avoid it be sound and politically OK? I think not.

OTOH, if the EU had forced things too much and had sent little green men to take Puerto Rico from the US, would be ok to send the US army to restore the status quo broken by an aggressive and unlawful move of the UE? I think in that case it would be OK, even if the population were mostly for the independence/annexation to the EU.
I think there are limits for everything, there is no universal rule for all cases, and every one is different from each other, so all cases must be taken one by one. No general rule works or is needed. It may sound a lot nihilistic, but I think that is how "Realpolitik" works. Every situation is different, so we should behave ourselves according to the circumstances, even is the situation seems the same.

The Iroquois nation appreciates your support.

Speaking of fighting in Crimea.... Robert Forczyk's WW2 crimea history, Where the Iron Crosses Grow, is free if you have audible.com membership.  Good book on the subject.  I read it some years ago.

Crimea will be fine without the water supply. Pre-2014, most of water usage in Crimea was agricultural in nature. Post-2014 Ukraine turned off the water supply but Russia was nonetheless able to keep the population supplied with water. And there's water stored in reservoirs so there will be minimal impact. So if the water gets turned off (again), the population will be fine.
Turning off the water is a key symbolic action that highlights the connection between Ukraine and Crimea. But it's unlikely to be operationally significant.

Part of ceding was hoping I could do my little part to make the discussion go away .  And I wasn't going to take the time to see if his data was any good, so was throwing in the towel because there's bigger hills for me to die upon.  
Meanwhile, I am wondering how the forum breaks down into UKR spring offensive camps.  I see two main camps in the world of internet opinion:
1.  UKR offensive will be big, sudden surprise attack on (mostly) one axis and we will know it's the real deal and will come late spring.
2.  UKR will conduct increasingly aggressive corrosion plus some attacks of small-ish depth, like 5-10 kms, in multiple areas to shape the battlefield and completely confuse Putin as to where to put his reserves.  Then will strike later in summer in a much bigger way and we will then know that's the real deal.
I am believer in #2

Now the problem with people constantly bringing writings of folks like Jefferson, Adams, Paine etc. is that they are only valid within American context. As much as I am fascinated by your Founding Fathers and their debates, please understand that around the globe they are not considered particulary relevant or inspiring political thinkers, nor is Declaration of Independence; at least not to the extent they are for Americans. Simply as that- American model of democracy, citizenship and political well-being is limited to US. Don't get me wrong, it's cool its there, USA is land of liberty, shield of freedom etc, but very few political entities (even most democratic ones) outside States were ever directly modelled by this system. Comparing it to political mentallity in Russia is material for a dark comedy in itself.
If you really need to support your claims, at least quote Monteskieu, Locke, Rousseau or Hegel- they did impacted political framework around the world in much more profound way. But of course none of them have anything to do with situation in Crimea either; it was simple, plain thugish land-grab by former imperial power modo mongolico.
Now extending your point, why not even Confederate States of America are  a thing anymore? They seem to enjoy rather popular acceptance. Except for slaves, of course.

So if I violently invade your house, kick you out, and when you try to get back, you get told "sorry, the people who live in the house decide", that is fine and dandy? Good to know, where do you live?
EDIT: the fact that the openly pro-Russia+pro-China commenter is actual Florida Man tickles my stereotyping brain in a funny way.

The Russians obviously aren't completely useless - they did manage to muster several hundred thousand folks at jump off points, get them across the border, and largely keep them there despite global sanctions, heavy heavy losses, and a pretty sustained Ukrainian offensive against their theatre logistics. If they were hopeless - or had become hopeless - then the Russian forces would already be back across the 2014 borders and Sevastopol's resorts would be taking summer bookings for Kyiv's great and good.
What the Russians don't seem especially good at is offensive operations. Much like the Germans from 1941 through to 1943, their offensive aspirations seems to be on a pretty sharp downslope^. Whether that's because they just no longer have the manpower, logistic support, materiel, and strategic surprise, or because all the folks who knew how to do that have had smoking accidents, been defenestrated, or afforded a close but brief inspection of the sharp end of a HIMARS I don't really know. I suspect, though, that is a combination of reduced materiel ability coupled with reduced cognitive ability. Which is predominant is a matter of taste in the absence of real data.
 
^ Compare Op Barbarossa to Op Blue to Op Citadel, then compare Feb 2022 to the dry humping now (still) going on around Bakhmut.