Having just seen IM3 I really do think Stark may return.
Also I'm starting to think maybe we'll see a masters of evil?
Red Skull - Not Dead
Abomination - Not Dead
'Mandarin' - Not dead
Aldrich - (I've got a feeling he could come back)
Loki - You never know with this guy
'If you meet a loner, no matter what they tell you, its not because they enjoy solitude. It's because they have tried to blend into the world before, and people continue to disappoint them'