I mean with custom nations you are free to invent any other AU stuff. Amani that remained united after the Second War, Ogre Kingdom in Arathi, Horde not losing completely but rather holing up and preparing for the next war, etc. Personally I'll go with the "boring" route, though. Quel'Thalas, probably reimagined by all the stuff introduced in the expanded universe and some of my own writing filling up the holes.