As long as it expand the world and have it evolve, i'm ok with it (Like the whole Forsaken thing, how they are going to deal with all this, and how the factions near Undercity act now that its unoccupied, how the Horde was most likely pushed out of that continent -excluding close to Silvermoon-, etc...)
I also wonder when this is going to take place, is this going to take place after Sylvanas destroys the Helm of Domination? if that's the case, it would make sense to see how the faction in the plaguelands deal with the rampaging scourge forces that are left there.