At first I figured it would probably focus on Adria, as that's a hugely important plot point that was left completely open at the conclusion of the game proper. But now I think it'll likely be something more minor than that, since they'll probably want to save their biggest story for last. So of the choices... I think it'll likely focus on Imperious.
He'll probably be either angry that you stole his thunder and swear vengeance on you, or he'll be (somehow) corrupted and generically evil. Either way, you'll be forced to take him out. And because it's an expansion pack, and takes place after the game proper, he'll somehow be more powerful than Diablo was so that he'll be a legitimate challenge to players, even if it makes absolutely no sense plot-wise.
That said, I won't be buying it. Diablo 3 started out as a reasonably fun game, got repetitive incredibly fast due to its fairly boring level design, fairly uninteresting character builds that lack D2's replayability, constant Blizzard trademarked buff/nerf cycles that render a class OP one week then worthless the next, and the auction house that the entire freaking game was developed around. If the expansion somehow manages to correct these problems I had with D3, I'll maybe consider picking it up. Otherwise, I have no interest in going back. I can get my grindy loot farming in more fun places like Guild Wars 2 or Borderlands 2.
ohnoitsabear said:
Although I must say, I prefer expansion packs to endless amounts of small, overly priced DLC.
Quoted due to my absolute agreement with this sentiment. I miss the expansion packs of the late 90's/early 2000's which were practically full games on their own.