I have to giggle at the 'anti-thrall' group being blamed in some posts, when it was simply bad storytelling to cram him down our throats for expansion after expansion, even if you were Alliance. 'Lets make up a fake title to give to him so he seems even MORE important!' 'Lets interrupt the blessing of the world tree for his wedding!' 'Yay you beat Deathwing! Now lets make the focal point that Thrall is having a kid!' Blargh. I liked Thrall in WC3 through Lich King. After that, just far too much.
I somehow doubt he'll come back as the Warchief. Kinda feels like his story in the limelight should stay done with, and I'd like to see other races beyond orcs have their story told.