I highly doubt it, but I'd like to see a makeover of the vanilla areas, repairing damage from Cata, and concluding the alliance vs horde stuff going on in the areas that were changed. It would be nice to see the terrible Cata writing nuked from orbit and have everything up to modern standards. I get that humor has always been in the game, but the pop culture references went overboard, and their fucking scat quest fetish is tiresome.
It would also fit well with the above suggestions of an expansion that doesn't deal with another universe ending threat right away. Things could appear to be more positive on the surface, but they could have some mystery in the game again, and hint at the threat that is coming.
Bonus points if they actually do something about TBC zones, and how fast you blow by the 5 level expansion content. Oh, and fix how you hear about what happened in WotLK, as in it's over, but then later on you go there and do that content. Pardon?