In a recent interview with Variety Robert Downey Jr. has confirmed that there are no immediate plans for a fourth Iron Man film.
When asked about the film, Downey stated “There isn’t one in the pipe. No, there’s no plan for a fourth ‘Iron Man.’” Though, he will reprise his role as Tony Stark in 2015’s Avengers sequel, The Age of Ultron and the yet-to-be-named third film in the franchise which is slated for release in 2018.
Source: Variety