1) Leah's soul is trapped in the Black Soulstone with the demons.
2) Diablo's form was destroyed, not his soul.
3) Tyrael is now mortal, so Imperius will despise him more.
4) Adria will seek out the Black Soulstone to resurrect ALL the demons.
5) Then there's the demon and angel that created sanctuary. I forgot their names. But what
role will they have if they return?
So many possibilities....so many expansions....