It’s hard to believe, but it’s been more than six years since Marvel introduced its cinematic universe with the first Iron Man film. But what happens when Iron Man — or Captain America and Thor, for that matter — don’t want to keep playing superheroes?

As we head toward Phase Three of the company’s master plan in 2015 with Ant-Man kicking things off, many of the franchise’s original stars are nearing the end of their initial (massive) contracts. Robert Downey Jr. re-upped through the next two Avengers films thanks to an absolute truckload of money, and he's reportedly going to play a big part in Captain America 3, but he’s free to walk after that. Behind him, Chris Evans and Chris Hemsworth are nearing the ends of their contracts in Phase Three.

After that? Who’s to say how long they’ll stay around the Marvel universe? Evans has already hinted he might want to hang up Cap’s shield once his contract expires, and you’d have to think the rest of the gang might also be looking to the next thing by the time Avengers 3 wraps up. Marvel is a notoriously stingy studio, and to this point, only Downey has had the leverage to command a massive raise to stick around. Sure, it's rumored they might bump the main cast to a massive post-Avengers 3 teamup, but that only prolongs the inevitable.

Downey was a special case on the heels of Iron Man 3 hitting the billion-dollar mark, and they won’t call in the money truck for everyone. Plus, as Marvel's shown with Guardians of the Galaxy, the company is certainly capable of launching new franchises — so it’d stand to reason that the law of diminishing returns would kick in once it reaches the point where they’d need to re-sign all of Earth’s Mightiest Heroes. Downey made $50+ million for The Avengers, and if you have a half dozen cast members pulling down that kind of dough, there’s no way you can make a profitable movie. It’s sad, but true.

So what’s the answer? Marvel plays things notoriously close to the vest, but studio head Kevin Feige has dropped some hints in recent years as to where the Marvel Cinematic Universe might be heading in the long term. Considering that Marvel has built its empire by locking actors into lengthy contracts, it’d stand to reason that Downey positively insane payout to stick around a bit longer is more the exception than the rule. Iron Man is the crown jewel of Marvel’s standalone franchises, and that status is reflected in the box-office take. If anyone can demand that type of special treatment, it’s Downey.

Though he’s locked in until Avengers 3, it’s certainly possible Downey could decide to walk once Phase Three comes to an end — or perhaps say farewell with one more adventure in the rumored Iron Man 4. He’s 49 right now, and he’ll be pushing into his mid-50s by the time Avengers 3 rolls around. Yes, the dude is awesomely charismatic and in extremely great shape — but the ability to play a billionaire playboy must have a shelf life. So will Marvel retire the franchise once he’s gone? That billion-dollar box-office haul for Iron Man 3 tells me it ain’t very likely.

So that leaves recasting the role. It’s hard to imagine anyone but Downey as that character, and we think Marvel will do whatever they feasibly can to keep him around as long as possible because he is so popular, but if The Incredible Hulk has taught us anything, it’s that Marvel has no qualms recasting a role if it’s in the best interest of the franchise. Mark Ruffalo stole the show in Avengers after stepping in for Edward Norton as the Hulk, and most fans would argue that was a stellar move. Toss in the fact that Tony Stark’s pal Rhodey magically changed from Terrence Howard to Don Cheadle in Iron Man 2 (which was also a solid decision), and there’s ample proof Marvel doesn’t mind swapping out actors.

Feige said as much in a 2012 interview, comparing the character to the long-running James Bond franchise in an interview with Badass Digest. A famed characteristic of the 007 franchise? A constant string of new actors taking on the title role, for decades at this point, but the story just keeps rolling along. If any modern-day franchise could match that success, it'd be Iron Man:

“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.”

After seeing what the Amazing Spider-Man franchise has done to Peter Parker’s box-office status in recent years (hint: it’s gone down -- a lot), we’d agree with Feige that a reboot is a terrible idea. At this point, virtually everyone on the planet has seen Iron Man. The last thing anyone wants is to have that origin story retold. We know it. It’s covered. Just keep giving us good new stories. Marvel has taken over Hollywood by taking the comics seriously, and constant rebirth is one of the things that makes them so timeless on the page. It might take a while to reach that point, but we’d expect Marvel to carry that concept over to the films sooner or later. New artists and writing teams come in to revitalize comics, and eventually, new actors will have to step in to play these iconic roles and keep them relevant.

So, does that mean Phase Four might bring all the characters we love with a new roster of actors bringing them to life? Honestly, probably not. Apart from Iron Man, The Avengers remains the big gun in Marvel’s arsenal. Yes, the other standalone franchises are very solid performers, but The Avengers and Iron Man easily lead the pack. So, how will they keep those team-up movies exciting? Much like the comics, you have to embrace change and keep evolving the concept.

Avengers: Age of Ultron is already poised to introduce Scarlet Witch, Quicksilver and the Vision to the cinematic universe — all characters who have played key roles in The Avengers pantheon throughout the comic canon. With films framed around Ant-Man and Doctor Strange waiting in the wings, it’s easy to see the other direction Marvel is heading here. Guardians showed they still have the mojo to launch a fresh franchise outside of the Phase One heroes, and Phase Three looks to bring a boatload of new heroes into the fold to fill out the roster for Phases 4-6.

Again, Feige has already hinted as much in a recent chat with the print edition of SFX. The Marvel comics are nothing if not full of potential characters, and if they keep digging, there are enough players there to fuel decades of movies. For Feige, part of the excitement is finding a way to work those new characters in to keep the concept of The Avengers changing with each film:

“I think it’s not a secret that Joss and I and all of us at Marvel think that part of the fun of Avengers is the rotating team, for sure.”

You can only have Iron Man, Cap, Thor, the Hulk, Black Widow and Hawkeye take on the Big Bad so many times before it starts to get stale. We absolutely love these characters, but we’ve been exploring them for the better part of a decade. If they want to keep it fresh, you must introduce new blood to the roster. Hell, who isn’t dying to have the Avengers meet up with the Guardians at some point? There are so many possibilities for interactions between these different characters, and don’t think Marvel doesn’t plan on mining that in the future.

So, what will Marvel do once the first phase of Avengers start to leave? We’d look for a healthy mix of recasting and new franchises to keep things going for the next few decades. Unlike most film companies, Marvel hasn’t spent the past six years building franchises. They’ve been building a universe. As the success they've had has shown, there's a big difference.

From Agents of S.H.I.E.L.D. to Netflix miniseries and the eventual Captain Marvel movie we’re all still waiting for, the MCU is filled with near-limitless possibility. Yes, we love the characters, but it’s also the universe that keeps us coming back. It's the scope of it all being interconnected that we love, and the way it opens up the storytelling in new and exciting ways. Other characters, and actors, can be just as exciting as the ones we know and love.

That universe is bigger than any franchise, and yes, even any actor.

What do you think? How can Marvel maintain its perch as a cinematic success in a post-original lineup world? Let us know in the comments!

