It's pretty widely known that Iron Man 3 was treated as the capper to Robert Downey Jr.'s solo trilogy of films for Marvel. The understanding, since then, has been that he'd pop up in Avengers movies- and perhaps the occasional cameo. However, there's been some recent speculation that there could be a fourth solo film for the character in RDJ's future. While in Toronto to promote his new film, The Judge, the actor addressed Marvel's plans once and for all.
"There isn’t one in the pipe. No, there’s no plan for a fourth Iron Man," he told the outlet.
The actor recently wrapped work on Avengers: Age of Ultron, the hotly-anticipated sequel that once again finds Joss Whedon in the director's chair. When asked if he'd ever "let" someone else take on the Tony Stark mantle, Downey Jr. thinks it's funny to think that decision would be his to make.
"I like that the idea is that it would be up to me, like I’m casting director for Marvel," he replied.
So it really would appear that his tenure with Marvel is winding down. Do you think they'll recast? That seems to be the widely-accepted solution, but really, they could just pivot things a bit. There's a new motormouthed wiseass in the Marvel Cinematic Universe, in the form of Chris Pratt's Star-Lord from Guardians of The Galaxy. I know Pratt is going to be involved in Avengers 3. And there's War Machine, who could satisfy the Mach suit action quota for future team-up movies. By subtly replacing the elements that RDJ brings to their movies, they may be able to avoid actually getting an all-new Tony Stark into the mix.
Just my 2 cents.