Remember Avatar? You probably do, because the film was a Titanic-sized hit for director James Cameron, taking in a worldwide box-office gross of over $2.7 billion, thus making it the highest-grossing film of all time. Yet despite this blockbuster status, Avatar seems curiously removed from the public consciousness. That’ll change soon, as Cameron is set to unleash four Avatar sequels upon the world. Maybe.

In a new interview, Cameron provides an update on his Avatar sequels, and claims that Avatar 4 and 5 are still not a sure thing. Cameron also reveals who Kate Winslet will be playing in the films, so read on to find out.

Hold on to your unobtanium, we’re about to take a lengthy trip back to Pandora with Avatar 2, 3, 4, and 5. Unless we aren’t. After a long delay, James Cameron surprised everyone by announcing he wouldn’t just be making one Avatar sequel, he’d be making four, with Avatar 2 hitting theaters in December 2020, and then a new sequel following it up for the foreseeable future. But not so fast, says Cameron. In a new interview with Vanity Fair, the filmmaker reveals that while Avatar 2 and 3 seem to be set in stone, Avatar 4 and 5 are still a bit up in the air:

“Let’s face it, if AVATAR 2 and 3 don’t make enough money, there’s not going to be a 4 and 5. They’re fully encapsulated stories in and of themselves. It builds across the five films to a greater kind of meta narrative, but they’re fully formed films in their own right, unlike, say, The LORD OF THE RINGS trilogy, where you really just had to sort of go, “Oh, shit, all right, well I guess I better come back next year.” Even though that all worked and everybody did.”

This seems like kind of a moot point, because the Avatar sequels will likely make a bunch of money. But it’s interesting that the sequels don’t seem to be as much of a sure thing as Cameron made them out to be in the past. The Terminator director previously claimed that all the Avatar films were being shot together as one large production. “It’s not back-to-back. It’s really all one big production,” the director said. “It’s more the way you would shoot a miniseries. So we’ll be shooting across all [Avatar scripts] simultaneously.” However, it now appears that only Avatar 2 and Avatar 3 are being shot together, and 4 and 5 remain in limbo for the moment.

In the new interview, Cameron goes on to reveal details about Kate Winslet‘s character in Avatar 2. Cameron says Winslet, whom he previously worked with on Titanic, is playing a member of the “Sea People”, and that the actress insisted on doing all her own underwater filming:

“She blazed through for a couple of days of rehearsals and saw the world that we had created, and how we do the work, and she’s very excited. She plays a character who’s part of the Sea People, the reef people. The one thing she did do is demand that she do all her own water work. I said, ‘All right, that’s fine, we’ll have to teach you how to free dive.'”

This confirms Winslet will be playing a motion-capture character, as Cameron recently discussed the exhausting process of shooting underwater mo-cap scenes. “We’ve been training [the cast] for six months now,” the filmmaker said, “with how to hold their breath, and they’re all up in the two to four minute range. They’re all perfectly capable of acting underwater, very calmly while holding their breath. We’re not doing any of this on scuba. And we’re getting really good data, beautiful character motion and great facial performance capture. We’ve basically cracked the code.”

Elsewhere in the interview, Cameron talks about his career in general, and attempts to drive a stake through the heart of the seemingly never-ending Titanic question: “Why didn’t Rose make room for Jack on the floating door?” Cameron’s blunt answer: “I think it’s all kind of silly, really, that we’re having this discussion 20 years later…It’s called art, things happen for artistic reasons, not for physics reasons.” There you have it: stop asking James Cameron about the ending of Titanic, because he’s not having any of it.

Avatar 2 will open December 18, 2020.