VIDEO: Marvel Teases 'Phase 2,' With 'Iron Man 3' and 'Thor 2' Footage and Other Details

"It got me thinking about how big the message from your cosmic sponsor needs to be before you pick it up," he tells GQ in a new cover profile. "How many genre movies can I do? How many follow-ups to a successful follow-up are actually fun?"

He reasons that, "I come from a family of very innovative writers and directors and actors and artists, and the circle of friends they were in were the people I heard having pun-offs playing poker at two in the morning, and it was just the most comforting aspect of my childhood. So there's this kind of legacy of souls from what I consider to be a very particular time in entertainment, and I'm sensing a return to that."

As for a time line, he points toward the three-year contract recently signed by New England Patriots quarterback Tom Brady, which will take the Super Bowl winner to his retirement. His contract is up, Downey says, and he's hoping to direct a Halloween-type horror film. He'll also star in the movie as "a Village Voice reporter on the run."

Whenever he finishes with Iron Man, Downey says, "I'm going to have a bit of a crisis, because I probably haven't even fully ingested how much I've enjoyed it, how much it's meant."

This summer, Downey will co-star in a film he is producing with his wife, a drama called The Judge, in which he plays Robert Duvall's son.

For more, click over to GQ.