As "Iron Man 3" continues to rake in the cash (it's surpassed the $1 billion mark worldwide and counting), everyone's abuzz about "Iron Man 4." Such an endeavor would seem like a no-brainer for Marvel, and the studio is completely dedicated to doing it ... whether Robert Downey Jr. is on board or not.

It's no secret that Downey Jr. has expressed reservations about returning for another stand-alone Tony Stark adventure, especially considering that it wouldn't happen until well after "The Avengers 2," which doesn't hit theaters until May 2015.

"I'd go start another one tomorrow, but it’s not tomorrow,” Downey told Entertainment Weekly, with the 48-year-old actor admitting that he's not getting any younger. "And there are a lot of other considerations. But I also don't like the idea of leaving people hanging or leaving people in the lurch."

RDJ is also anticipating a career beyond Tony Stark and Marvel, which may include a third "Sherlock Holmes" movie and even some brand-new franchises.

"My intent is to launch another franchise, independent of any that I can even imagine right now," said Downey, who's also currently attached to David Dobkin's legal thriller "The Judge" and Jon Favreau's foodie comedy "Chef." "My intent is to dominate the playing field for as long as I can, with my own challenges, with myself."

That's swell and all, though Marvel has made it clear that there will be an "Iron Man 4" (and beyond) with or without its leading man. The series could certainly be rebooted James Bond-style, despite the fact that Downey Jr. is so singularly identified with the role.

View photos Robert Downey Jr. and Kevin Feige More

"I believe there will be a fourth 'Iron Man' film and a fifth and a sixth and a 10th and a 20th," said Marvel producer Kevin Feige. "I see no reason why Tony Stark can't be as evergreen as James Bond. Or Batman for that matter. Or Spider-Man. I think Iron Man is a character just like that."

Don't think Marvel won't do it, either -- they've already replaced Edward Norton with Mark Ruffalo as Bruce Banner, not to mention Terrence Howard with Don Cheadle as James 'Rhodey' Rhodes. Heck, don't think Marvel just won't replace everyone in "The Avengers 2" if the ensemble doesn't agree with their terms.

According to Deadline, Marvel and Disney are heading into some troubled waters with "The Avengers 2" as the upfront pay, backend compensation, break-even points and box office bonuses aren't pinned down yet for several cast members. The studio is notoriously stingy, and while they're usually successful in keeping at least the details of any tensions from the media, they still inspire some frustrated venting from actors' reps.

"Marvel has created so much animosity by strong-arming and bullying on sequels already. It's counterproductive," said one source to Deadline. Says another, "I'm sick of Kevin Feige telling me again and again how Marvel is 'reinventing the movie business.' It doesn't work like this. They're reinventing business, period."

That "reinvention" may involve just bringing in a bunch of replacements to play the superheroes we've come to know and love in "The Avengers 2." We highly doubt it will ever come to that, as public backlash would be mightier than Thor himself, but it definitely makes for an almost diabolical negotiation position ... after all, we doubt any of the "Avengers" stars would want to see someone else literally stepping into their shoes (or boots, rather).

However "The Avengers 2" works out, it will mark the end of Marvel's Phase Two (which commenced this month with "Iron Man 3") and set the stage for Phase Three. There's currently only one confirmed film set for Phase Three (though you can probably also definitely count on "Iron Man 4"), with the rest of the candidates merely speculative ... and some more realistic than others.

"Ant-Man"

The tiny but rollicking adventures of size-shifting scientist Hank Pym have been in development since even before the first "Iron Man" and will finally be hitting the big screen as the official Phase Three blast-off. Pym develops a suit that allows him to shrink to the size of a certain insect ... and to communicate with them as well.