The latest "Iron Man 4" rumors started when Robert Downey Jr. revealed that he will not be appearing in the new sequel. He first told Ellen DeGeneres that there are negotiations for a fourth installment, but he later on told David Letterman that he will not be appearing in another "Iron Man" movie and instead do other stuff with Marvel.

Apart from "The Avengers: Age of Ultron" and the "Avengers 3", the 49-year old actor may also appear in "Captain America 3". Variety reported, "Robert Downey Jr. is on the verge of signing on to Captain America 3 with Tony Stark's Iron Man set to play a key role in bringing the Civil War storyline from Marvel's comic books to the big screen and trigger the start of a new phase of movies from Marvel Studios."

The website revealed, "The actor is in final negotiations to play the billionaire in the yet-to-be-titled third installment, that is slated to begin production in the Spring for a May 6, 2016, release, according to sources close to the discussions."

Robert Downey Jr. seems to have a pretty tight schedule with Marvel Entertainment, but many fans still want to see him in another "Iron Man" movie. But based on the "Iron Man 4" rumors and reports, the chances of him doing another solo movie about the iron-clad superhero is pretty slim. So now what would Marvel do without him?

Badass Digest asked Kevin Feige what their plans are when Downey decides to retire from doing "Iron Man". The website also asked if they would reboot the series or would it be like (pre-Casino Royale) Bond, where a new guy took the role and nobody said anything.

The president of Marvel said, "I think Bond is a good example. Let's put it this way: I hope Downey makes a lot of movies for us as Stark. If and when he doesn't, and I'm still here making these movies, we don't take him to Afghanistan and have him wounded again. I think we James Bond it."

In case the "Iron Man 4" rumors are true that Robert Downey Jr. will be replaced by another actor, who do you think will become the new Tony Stark?