Much has been argued on the Internet recently regarding the future of the Marvel Cinematic Universe. Come the culmination of Phase 3 with Avengers: Infinity War in 2019, the next phase will be an interesting challenge for the head honchos at Marvel Studios. No one has any idea what producer-extraordinaire Kevin Feige has planned - but you can bet dollars to donuts that he'll be intent on topping the quality of Phase 3.
With Age of Ultron making slightly less money than the first Avengers instalment, there may be some fear at Marvel that Infinity War could also under-perform. There is a very distinct chance that it could suffer from audience fatigue: there's already a lot of continuity in place for regular filmgoers to follow and it's only going to get more convoluted.
If that reaches breaking point, we could see a variety of changes happening at the onset of Phase 4.
It'll be a case of examining potentially diminishing box office returns (admittedly unlikely, as far as the upcoming Captain America: Civil War goes - which looks likely to go on to be Marvel Studios' top-grossing non-Avengers film) and checking whether any of the franchise luminaries want to stick around; after all, Robert Downey Jr was only just about kept around to butt heads with Cap next year.
Let's take a look at some of the options confronting Marvel come Phase IV; be it continuing their story-lines with current supporting characters, recasting all their major heroes or starting entirely from scratch.
8. Passing On The Mantle
Within both Marvel and DC comic book continuity, superhero mantles are constantly being passed down to those equally deserving, once the originals decide to hang up their shield, or gauntlets, or hammer. So why not adopt the same trend in the Marvel Cinematic Universe? Marvel have already released one mantle-passing movie in Ant-Man, and there is now precedent to start replacing actors who don't want to continue.
In the comics, when Steve Rogers dies, Bucky Barnes takes up the mantle - at least once he shakes off his Winter Soldier mind-control conditioning. Following that, and more recently, one-time sidekick and fully-fledged Avenger The Falcon has adopted the shield, blended with his unique fighting style and aesthetic. Either of these are a natural option to replace Chris Evans and Marvel would also reap heavy rewards in the media for having an African-American Captain America on the big screen.
Likewise, in the comics, Rhodey takes over the Iron Man mantle once Tony Stark is unfit to continue on. And in Don Cheadle, Marvel have an Oscar-nominated actor who could more than capably carry the weight of a franchise heavy-hitter on his shoulders. He's also already proved he has the screen presence and personality to carry it.
As far as Thor goes, Chris Hemsworth shows little sign of growing disinterested with the franchise; yet, in the eventuality that he did want to depart the now-hallowed halls of Marvel Studios, we have a new, female Thor inhabiting his role in the Marvel comics continuity. And she's already in the MCU as well, of course.