Originally Posted by Spider-Fan
Iron Man 4 isn't likely until after Avengers 3, so this won't happen for a while.
But on this topic, I see 2 decent ideas here: either Zeke Stane hires Ghost to get revenge on Stark. Or, the Ten Rings and AIM go to war with one another, and Iron Man gets in the middle.
Post-AHTK, this makes the most sense.