With "Iron Man 3" setting box office records around the world (read our review of the film here), speculation has already begun about the possibility of an "Iron Man 4." There's just one wee problem: Star Robert Downey, Jr. has publicly stated that he will likely hang up his armor for good after "Avengers 2" comes out in 2015. So that means the "Iron Man" franchise has come to an end, right?

Well, maybe not. After all, Disney and Marvel have some pretty good reasons to keep the series going.

Several billion of them, in fact.

Now, the most likely scenario is that Disney will throw a hundred million dollars at Downey, Jr. and persuade him to stay on. But if that fails, the folks at Marvel still have two other options: Recast the role, James Bond style, or just put another character in the suit.

So with that in mind, we've put together a list of nine possible replacements for Robert Downey, Jr. in "Iron Man 4." Because the world isn't just going to save itself, now is it?

Johnny Depp

Replacing an international superstar like Downey, Jr. is no small task. But if anyone can pull it off, it's Johnny Depp. Not only is he arguably an even bigger box office draw than Downey, Jr., he also has both the look and the sharp wit needed to portray Tony Stark. Perhaps most importantly, he has an ironclad relationship with Disney thanks to his four "Pirates of the Caribbean" films. It's hard to think of a better option to fill the Iron Man armor.

Ben Affleck

While Ben Affleck isn't the most obvious choice to replace Downey, Jr. (see above for that), he does have a few things going for him. First, he's eight years younger than Downey, Jr., meaning he has more tread on his tires. Secondly, he's hungry to cap off his amazing career resurgence, and there's no doubt that taking on the role of "Iron Man" would validate him once and for all as an A-list star. Plus, adding Affleck as an actor might convince him to come aboard as director as well, which would certainly be a coup for Marvel. Sure, he would be a slightly more serious Tony Stark, but he has experience both in superhero films ("Daredevil") and growing great facial hair. We'd go see it.

Ryan Gosling

Speaking of younger options, Ryan Gosling has the intelligence, intensity and charisma necessary to portray cinema's leading superhero. We would have some concerns over his style; traditionally, Gosling's characters have been much understated than Downey, Jr.'s frenetic, borderline hyper Stark. But we'd love to see Gosling try and stretch his acting muscles in that kind of a role. Plus, as the sexiest man alive, Gosling certainly can command attention, something that any perspective Iron Man needs to do.

Clive Owen

One of the most underrated stars out there, British action icon Clive Owen has pretty much everything going for him. Not only does he look like Tony Stark (have you seen Owen with a goatee? It's almost eerie), but he's also cerebral and has displayed a wicked sense of humor in films like 2007's "Shoot 'Em Up." Sure, the accent might be a slight issue, but Owen is a professional, so we're sure he can master an American sound. And we're even more sure he could pass muster with American audiences.

Dominic Cooper

We already know that Dominic Cooper has what it takes to play a Stark. After all, in 2011's "Captain America: The First Avenger," Cooper played Tony Stark's own father, Howard Stark. So with that family resemblance already established, why not give Cooper a shot at the big time by promoting him to the lead in "Iron Man 4?" Cooper has earned critical acclaim in smaller films like 2011's "The Devil's Double," but so far he's never had a chance to really show the public what he can do in a major leading role. And for Marvel, it could be the best of both worlds: By creating a new star instead of signing an established A-lister, they would save themselves a ton of money while building up new buzz. Win-win.

Zac Efron

Okay, stay with us for a second. On the surface, this sounds like an insane pick. And it is. Once upon a time in the comics, though, Marvel totally lost their minds and dumped the Iron Man everyone knows and loves in favor of Teen Tony, a high school aged Tony Stark brought in from an alternate universe to replace the real Tony Stark. Sure, it's widely regarded by fans and critics alike as the worst Iron Man story of all time. Because it totally was. But since they did it once, we know they can do it again — and if they do, Zac Efron would be the perfect pick to play the untested young hero.

Gwyneth Paltrow

Fans already know from the trailers that Gwyneth Paltrow's character Pepper Potts ends up donning the Iron Man armor at some point in "Iron Man 3." So why not make the change permanent? Pepper has already shown in the first two movies that she's got the brains to run the whole Stark operation. So if Tony wants to retire and focus on inventing new uses for his arc reactor technology or something, we're sure she could step in and become the new Iron Man without missing a beat. And hey, it's the 21st century. It's about time we got some serious girl power.

Don Cheadle

Logically, if Tony Stark calls it quits as Iron Man, it's Don Cheadle's military hero James Rhodes who should take over. Not only has Rhodey done exactly that several times in the comics, he's already proven he knows how to rock a suit of armor as War Machine in "Iron Man 2." Plus, the fact that Cheadle is even in these films is proof that recasting and re-imagining roles can work; after all, he replaced Terrence Howard, who originated the role in the first "Iron Man" film.

Paul Bettany

Finally, if Robert Downey, Jr. doesn't want to wear the suit any more, why not just let the suit handle crime by itself? Yes, enter Paul Bettany, who over the first three films has become very familiar to fans as the voice of Jarvis, Tony's super-intelligent AI operating system. It's Jarvis who calculates the odds, regulates the power output, runs the targeting systems and does, you know, all the hard work. Tony just takes the credit. So in "Iron Man 4," how about we cut out the middle man and finally give the Iron part of Iron Man the credit it deserves.