Well since we kicked them out of Pandaria, the Zandalari still need a new home.
And now, they don't just have a new continent to conquer, but whole world of Draenor...
As many have said Vol'jin is Warchief, so expect some involvement from him during the expansion. If he isn't featured on Draenor's storyline, then hopefully there'll be a troll patch, and murlocs should also appear in a future patch (that returns us to present-day Azeroth).
Isn't it ironic how education is important, yet people forget all about it when they visit the internet?
A troll raid or dungeon patch is mandetory expansion content, we certainly will see Trolls.
It's like an in-joke sort of.
I love the look of Trolls raids, but the armor always looks awful (imo) like the stuff from ZA, some people like it though so it's cool, plus we have transmog now.
Well that may be nice for Alliance players, while us Horde players will have to suffer through having one as our leader.