It's the movie franchise that put Robert Downey Jr back on top as one of the most in-demand leading men in the world, but we might be waiting a long time to see Iron Man lead another film with top billing. The Marvel machine is now churning out two to three blockbusters a year in a golden age for comic book movies. With Avengers: Age of Ultron fast approaching and Avengers 3 in the pipeline, many fans have assumed that Iron Man 4 must not be far behind. Not so, says its star. Speaking with Variety at the Toronto International Film Festival, Robert Downey Jr. has once again confirmed that all he is currently signed on for are the two Avengers sequels. “There isn’t one in the pipe,” Downey Jr told the magazine. “No, there’s no plan for a fourth Iron Man.” At this point it's hard to imagine anyone else ever playing Tony Stark...