The GoT Aftermath: Quo vadis, George?

Dany's unfinished business:

Unite the Dothraki, deal with Meereen, secure passage to the west, (possibly) deal with Dragonbinder, deal with Young Griff, deal with the fallout of bringing Dothraki into Westeros as an invasion force, fight the Others, and the ultimate question of the Iron Throne

As you say, the only way to deal with all of that is for it to either be as rushed or unsatisfying as in the show, or (more likely) that it'll take more than two more books to finish.

Edit: Since you brought up his tendency toward rewriting, I wonder whether or not the series might have progressed faster if he'd just said "fuck it, this will be finished in however many books it takes," rather than setting these weird, arbitrary goal posts that he tries to meet, spending years mired in endless rewrites before Anne Groell finally convinces him to push some stuff to the next book, and publish what he has--which isn't just what happened with AFFC and ADWD, but with every book in the series except for ASOS.

Small thought experiment. Imagine it's 1978 or whenever the fourth book came out, and you wanted to make a thread like this. What does George need to do?

Then imagine picking up Dance and reading a million words about Quentyn Martell.