Apparently as the only member her to have ever served on an Iowa class Battleship, let me clear up a few things.
1) All 4 Iowa's still have all 3 16'' turrets. There was some talk back in the late 80's with the Missouri and the Wisconsin of trying to remove the 3rd turret to make vertical launch tubes for missles, and also more talk of an under deck hanger of some sorts, but it couldnt be done as the turrets just weighed too much and she ship needed the weight to remain stable.
2)All 4 Iowa's carried 8 ABL capable of carrying 32 Tomahawk Missles and then another set of launchers(not armored for 16 harpoon anti ship missles, As far as the tomahawks go, and I doubt anyone will ever find any true reference to this but some of the tomahawks were nuclear tipped .
3)Each Iowa started with 10 dual 5"38 gun mounts 5 on each side of the ship, in the 80's reto the removed 2 mounts from each side, leave 12 5'38 barrells, 6 in 3 mounts on each side of the ship. On a side note the Marine manned mount, which I was a crew of was the only 5" mount to get a fire mission in Beruit(i guess it was symbolic, Marines supporting Marines) Anyway, we took out a Sryrian gun battery, spotters confirmed 22 killed. Inside the mount some sailor art was drawn depicting a silloutte of a man with a raghead with a circle around it a a line going through it diagonally with"scatch 22" written above.
4) There are lots of reasons I think they were retired. There used to be a website around called Warships1.com ran buy a guy named Guy Derdall or something like that, and there was a poster there that was pretty high up in the chain of commaned at Long Beach Naval shipyard that refitted 2 of them. wish i remembered his name, anyway, his though was that the 16" barrell liners and extra barrels were all goneand no way to reproduce them.
5)With the range of the 16" barrels at about 25 miles there was in development in the late 80's a round capable of ranging out to 100 miles, If the BB's had stayed in service im sure it's reasonable to assume that todays technlogy we would certainly 100 mile and more ranges from the 16's