I think a campaign could be done if enough liberties are given, I mean this is for entertainment purposes...
I imagine a scenario where both sides have sustained heavy losses in a blow for blow kind of engagement that's left thousands of Chinese Marines and Army stranded on Taiwan beachheads as the Chinese Navy sink off the coastline. Xi being determined to salvage the invasion, for his own sake if nothing else, plays the conflict as partially successful and orders his remaining forces to push inward.
Chinese have to push inland, knock out remaining enemy AA systems, repel counter-attacks to avoid being driven back into the sea, cause havoc etc, while Xi has his generals scramble to get reinforcements and supplies to Taiwan beachheads. Taiwan obviously have to prevent the Chinese from succeeding, so the campaign has various mission types, attack, defend etc.
Eventually, despite their best efforts, Taiwan fail to stop the Chinese resupplying and reinforcements being to trickle in, this triggers Japan and US Marines to get involved, Australia too, (of which all three will be DLC $$$$) and now you have various conventional and asymmetrical battles going on all over the place.
And as a new edition to the series, it can include Horde Mode, which actually takes place on a small Japanese island that Japanese Marines defend, savage combat against waves of Chinese Marines and Army, and you can upgrade your Japanese forces as you go on.
I'll be waiting for the devs to contact me to discuss my cut
hahah but seriously someone needs to do this I'm sure people will play.. heck just make the Chinese faction playable with their own campaign... hmm online play China vs Taiwan.. are we not seeing the possibilities (ramifications) here?!? lol