Seems Marvel were considering T.I. for a role, but he had to decline due to scheduling. I can't imagine the role, but it would have been cool having him there.
“I was being considered for this one film. Now that it's over with, I can say it. Iron Man 3. I was being considered for Iron Man 3 and it wasn't to be Iron Man, it was to be another character in the film but our schedules did not align and they had to do their movie anyway. I told them go on ahead, I didn't want to get in their way. [laughs] But yeah man, I mean, I think my dream movie is an action-comedy. I want to do another Lethal Weapon or 48 Hours or Bad Boys. I want to do those types of movies.”