There are odd reports floating about that Robert Downey Jr. could be replaced in "Iron Man 4" by a teenage actor. Both Fansided and Moviepilot have theorized by taking the latest internet rumors that latch on to points of information and then draw lines between them, even when there's no real reason for doing so. Sites are actually reporting that Ty Simpkins (who you'll see next summer in "Jurassic World," unless you hate fun and dinosaurs for some reason) is going to take over as Iron Man for a hypothetical "Iron Man 4" in 2019.
Their reasoning (if you want to call it that...)? Well, Simpkins was already in "Iron Man 3" as Harley Keener, the kid who helped Tony get his act, and armor, back together. Maybe Tony will hand off the identity to him. Or maybe Marvel will just cast Simpkins as a younger Tony, since he looks like him. No joke, someone actually wrote those words and put them out there in the world for people to read.
Considering Simpkins is just 14 now, and would be only 17 or 18 if and/or when they got around to shooting an "Iron Man" movie for 2019, I'd be willing to bet my substantial video game collection that there are no plans or discussions on having him in the suit for Marvel's Phase Four.
Yet, there was an actual story arc in the comics where Iron Man was turned evil by Immortus and the Avengers used a time machine to collect a young Tony Stark from the past to help in the fight with his evil, future self. In that battle, the young Tony is wounded and yes, you guessed it, he now needs an Iron Man chestplate/arc-reactor to survive.
Anyway, the older, evil Tony martyrs himself to save his younger self, and Teen Tony was an actual thing for a while. And it was dreadful. There's no way in hell Marvel puts us through that nonsense in movie form.
Or do they...?