I hate to jump so far ahead here but thought i'd just make a point of this.
They said the conclusion of WoD would lead pretty heavily into the next expansion.
Given the whole orc corruption thing, Grom, and the lack of mention of Gul'Dan i'd be pretty shocked if it didn't directly lead into the burning legion expac.
It'd feel weird the orcs story spilling into Azshara/N'zoth and they all but destroyed the idea of an Emerald Dream expac