With Robert Downey Jr. looking to move on from the role of Tony Stark after a fourth movie and two Avengers installments, could he be re-cast as Stark or could they just pass the role along, much like what will happen with Chris Evans and Captain America?

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While it was originally Terrence Howard in the role, Don Cheadle has played James Rhodes for the past two Iron Man movies and will reprise the role once again for Avengers: Age of Ultron. So could he be groomed to take over for Downey Jr. and the Iron Man franchise?

Much like Anthony Mackie or Sebastain Stan taking over for Chris Evans after Captain America 3, it could be a similar situation for Cheadle and Iron Man 4. The actor has pretty much been there for the entire growth of the Marvel Cinematic Universe and would be a due a leading role in a big movie.

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In the comics, Rhodes served some time at Stark International as Stark's pilot and became Tony's close friend, risking his life to aid Tony against enemies such as Justin Hammer and the Maggia. He watched helplessly as Stark gradually gave in to alcoholism.

After a humiliating defeat battling the villain Magma while intoxicated, Iron Man went to Rhodes for help recharging his armor and inadvertently revealed his identity. Too inebriated to continue his fight with Magma, Stark passed out and Rhodes donned the armor, becoming Iron Man for the first time. He saved Stark International from Magma's rampage and Stark asked him to continue as Iron Man.

While the story could be re-worked a little, it would be a way to put Rhodes in the Iron Man suit moving forward and let Downey Jr. move on from the role. But Marvel may have a tough time doing this because, contrary to Captain America, Iron Man is Downey Jr. and he is as much a selling point as the Marvel brand is at this point.