When asked point-blank on the "Late Show" whether there's going to be another Iron Man solo movie, Downey said, "Just between us, no. But, I'm going to do other stuff with Marvel. I'm still going to be involved with Marvel and there's going to be plenty of fun stuff to happen."
What could that "other stuff" be? Here are a few possible scenarios.
Since Downey's current Marvel contract only covers him for "Avengers: Age of Ultron" and "Avengers 3," even the smallest appearances of Tony Stark would require re-negotiation. Since Iron Man is the biggest star of the Marvel Cinematic Universe, the company has mostly reserved him for his own movies, but there's no reason that he couldn't make a cameo like he did in "The Incredible Hulk" again.
2. TV Shows
Even though Downey said that he'd like to show up on "Agent of S.H.I.E.L.D." something gives me that feeling that an appearance on one of Marvel's Netflix shows seems more likely. "Daredevil," "Jessica Jones," "Luke Cage" and "Iron Fist" are all in New York, Tony's new base of operations, and the trip from Avengers Tower to Hell's Kitchen isn't far at all.
3. Giant Crossover Films
A rumor that began over at Badass Digest has lots of people rethinking the future of Marvel. Keeping it short, the theory is that "Avengers 3" is only a set-up for an even bigger crossover movie that would bring every Marvel Studios character together. If this is the case, Marvel would definitely have to extend Doweny's contract or keep him out of "Avengers 3," but without knowing the specifics of the legalese, I'm not sure if that's an option.
4. Supporting Character
Since Marvel is currently trying to establish the next generation of heroes, who else is better suited to help give an up-and-comer, like War Machine, a leg up than Tony Stark. Sticking Iron Man in a supporting role to help bolster a less known hero could make a solo series that might not otherwise exist possible.
"Avengers: Age of Ultron" opens in theaters on May 1.