The Marvel Cinematic Universe has been a bold experiment in franchise universe creation, but suffice to say it has paid off dividends for Marvel, Disney, and all those in Hollywood who have benefitted from the trends Marvel Studios has set.
However, as the MCU continues through Phase 3 and edges closer to the big Avengers: Infinity War crossover event, fans are beginning to wonder what kind of changes they will see in the aftermath of Infinity War. Marvel has been clear in its claim that Phase 4 will introduce a new sort of MCU, with new characters and relationships to explore. It will also be a time when contracts with some of the bigger stars may be done, and their solo character franchises exhausted. It all leads up to an inevitable point where the MCU superheroes will need to be recast.
Marvel Studios head Kevin Feige has addressed the issue of recasting several times over the years, usually getting by with the statement that the time for recasting is still far off. Feige told Variety magazine, "look to history: We have a new Spider-Man right now who was in our “Civil War” film and is in “Spider-Man: Homecoming,” and the audience has embraced it. And you can look to Sherlock Holmes, James Bond, and Batman as characters that last longer than any one actor playing them. There’s a precedent for it in other franchises that suggests it’s possible. But right now I don’t want to think about it and don’t need to think about it."
There is already a well-established precedent for popular action and/or superhero movie characters being recast. On the other hand, it may actually be too hard for fans to see someone else besides Robert Downey Jr. playing Tony Stark, or someone other than Chris Evans (and his pecs) as Steve Rogers. Marvel has actually spent the last few years laying foundation for transition in the comic books, by having new and different characters inheriting the iconic mantles of characters like Iron Man and Cap. So if/when RDJ is done in the MCU, then a young black female actress can be cast as Riri Williams, the new Iron Man (or "Ironheart") in the comics. With Evans it's even easier, as both Anthony Mackie's Falcon and Sebastian Stan's Bucky are possible fill-ins as Captain America. Thor is now a female... the list goes on.
