I didn't insult him, Fiona. The point is it is a fact that an actor will always be replaced by somebody younger as he gets older. They have done it with James Bond, for example. Imagine Angelina Jolie was in her late forties or early fifties when they decided to make a new Lara Croft franchise. Do you think they would hire her again for the role? I don't think so, because she would be too old. They would hire a younger actress.
Don't get me wrong. Robert is great as Tony Stark. He has made this character his own. Granted, his acting made the Iron Man movies a huge success. However he will be replaced by a younger actor some time in the future, like any other actor in a movie franchise. That's inevitable.