Avengers: Infinity War - 8 Compelling Hints Iron Man Will Die (& 4 He Won't)
3. Robert Downey Jr "Can't Do It Forever"
Permanently killing a huge character in a franchise like this is one of the easiest means of manipulating a huge response from the fandom, but the simple fact is that it diminishes in potency as the actor stays in the role because of a simple fact of existence. Just as everyone dies, the life-span of an actor in any role - even one as lucrative as a masthead MCU character - is subject to the rules of mortality. In short, no character can live forever (or at least not with the same actor behind it).
And it's not like RDJ has been shy about talking about his retirement from the character. He's gone more quiet on that front recently - probably to throw us all of the spoiler scent - but back on the set of Civil War, Downey, he talked about his advancing years:
"I also recognise that Ill be turning 50 by the time I promote this movie. The clock is ticking down on the amount of memories and participation that I would allow myself and not embarrass the medium with."
Doesn't that sound like someone committed to going out with a bang, rather than a whimper?
And before anyone says Tony Stark could be replaced with another actor... No, he absolutely couldn't. Without Downey Jr, there would be no MCU Stark and the character's arc in the films has been increasingly invested in his fears of mortality and how suitable he is to remain as an active superhero. Making him have a change of heart just to suit the change of face would be a huge disservice.