With all the talk going on what or who will be in the Expansion, I guess I should put in my 3 cents. First let me point out, these are the characters I see appearing in the game because of their importance.

1) Imperious
2) Adria
3) Leah
4) Theives Guild

The main argument going on is that the black soul stone is destroyed. After watching and re-watching the cinema, I thing that the stone is still in tack, maybe not what it use to be, but it is there. Also if you go back through the cinema, Imperious and his buddies are a little p.o'd with Humanity, so this is were I think the stone and Imperious come into play. At the end of Act IV Tyreal approachs us and tells of a great danger ahead of us as Imperious is searching for the world stone. He tells us that Imperious can not get his hand on us and that if we get it first we will be able to assist Leah, Upon hearing this he sends us to Kingsport. Wwe will find ourselves teleported to the city of Kingsport (theives guild area). Where we will face off with the guild and eventually set about heading off to face our new adventure. Along the way we face off against those angels who turned against the counsil as well as find out what happened to Adria. Eventually we will meet Imperious again, but he has found the world stone which alters him and the fight begins.

If you win the battle you release Leah and she is sent to heaven where she will take her place among the counsil.