The next Iron Man film appears to be very much about a past Iron Man storyline, and it's not derivative of what we saw in Avengers. Comic fans may be familiar with the Extremis storyline. I can't say that I am, but that's where the rumors for Iron Man 3 are pointing. Additionally, Ben Kingsley has been cast for the movie, and is rumored to be playing the Mandarin. Personally, I can't think of a more significant villain from the Iron Man canon.
Thor 2 is in the works, too. That movie seems poised to show us more of the expansive universe outside of Earth and Asgard. Plus, when you consider the fact that the object of Thanos' desire, the Inifinitey Gauntlet, showed up in the weapons vault on Asgard? I think that Thor 2 might be the vehicle for further developing the plot involving Thanos.