MoP will not have one villain, like the last three expansion had. Instead, it will be more similar to classic WoW. That's great. But is it possible?
I appreciate that Blizzard doesn't introduce the next super-villain with MoP. In fact, I criticized this about Cataclysm. Back then Blizzard said that they really think that one big evil dragon is good. And I really disagreed that it's that simple. Blizzard really needs to employ some Hollywood writer not to write quest text, but to explain to them the basic components of a good story. Watching this Extra Credits Episode would be a first step.
A super-evil, super-huge dragon that destroys stuff in a totally arbitrary manner and obviously wants to wait with the ultimative Armageddon until after you have killed him, just doesn't work. Even if I concentrate really hard to suspend my disbelieve: this is just too much. In fact, a lot of players laugh at you, if you mention that you sometimes think about the narrative in WoW. I think this shows that there really is a problem.
This doesn't mean, however, that just omitting that villain solves anything: he needs to be replaced! And if Blizzard manages to replace him with the kind of adventure that classic WoW was, I would be very, very impressed. Of course, this is impossible if you design this game for Kingslayers and Dragonslayers. Blizzard must make us forget that we just slayed the Destroyer of Worlds, ancient crazy Dragonaspect of Earth. And they must immerse us into less 'epic' stories.
This is not impossible. But looking at Blizzard's past performance when it comes to scaling 'epicness' down, I am not all that optimistic. Moreover, the player base is not used to this. They will - rightfully - ask the question why it required the Saviors of the Azeroth to rescue the cute little Panda child and her puppy.
While saving little children from danger is inherently heroic, it is also very far removed from the things Blizzard has told us are heroic in the past. This scaling-down, while arguably necessary, will prove very difficult.