Re: Downey's last?
You know, I mean...now that I'm thinking about it...
If you've seen the guy at comic-con, it's pretty obvious that he loves the fans and loves what he's doing. He also obviously likes keeping busy with his movies. Maybe he would be willing to continue as Tony Stark past IM3.
After all, after IM3, I could see them putting the Iron Man franchise to rest for a little while and just having Tony show up in other Marvel films. That would only require RDJ to show his face for a few minutes here and there. Otherwise, he'd just lend his voice to the visual effects of Iron Man flying around and kicking ass...
Phase 1 >>> IM - TIH - IM2 - Thor - CA: TFA - The Avengers
Phase 2 >>> Iron Man 3 - Thor: TDW - Captain America: TWS - Guardians of the Galaxy - The Avengers 2 - S.H.I.E.L.D.
Phase 3 >>> Ant-Man - Doctor Strange