Director Paul Greengrass and actor Matt Damon recently held a press conference for their upcoming film Green Zone, which arrives in theaters March 12, but the big topic of the day was the uncertain future of the Jason Bourne film series and the fourth Jason Bourne film that Greengrass stepped away from last November. Here's what Greengrass had to say about his departure.

"Listen, I just love the Bourne franchise, number one, and I owe it a great deal, and I gave my all on the two films that I made," he began, "But when I was honest with myself last Autumn, and I was starting to get going on other things, you just come to a point where you realize you've done it. You don't have anything more to contribute to a franchise that needs to continue obviously, and in order to continue, a franchise needs to be rebooted and reenergized by new perspectives. I just felt that I'd done it, and there's nothing unnatural about that. To make a film, it's 19 months of your life seven days a week, 20 hours a day, you've got to have real... and there were just too many other things that I was interested in. I felt like I'd had a wonderful, wonderful time, I loved it and I want it to continue. In the end, contrary to reports, there was never an argument with the studio of any kind at all. I did spend some time thinking that I might (do it) and getting myself to a place of 'what would it be?' and it's only when you do that where you find, 'You know what? I'm gone. I'm onto other things.' I explained (it) to them. We had a very nice discussion--they were completely understanding--and I said 'We'll make some other movies.' They said 'Excellent.'"

Matt Damon recently revealed that this new Jason Bourne film could be a prequel, with a new cast and crew, before Damon and Greengrass returned to the series. Damon clarified those remarks at the press conference.

"I think they have a good way to do a prequel with someone else, and basically make it about the Bourne identity, the actual identity. Any studio is interested in making it an evergreen that can just go on and on and on, and it never will with our character because he's resolved his issues now. He's got his memory back three times now. I don't think anybody wants to see me say 'I don't remember' again, but I think what we could do is that you can do some movies with another actor, anyone, whether it's Ryan Gosling or Russell Crowe or Denzel Washington, and he's Jason Bourne, and at the end of his one or two or three movies, you see them getting ready to pass the identity onto me, so it just becomes like a 007, it becomes the name that they give this certain person who is uniquely positioned. So then if Paul and I come back and do a fourth one in ten years, we'll pass it onto someone else and then the thing can kind of go on."

Damon also spoke about the True Grit remake he'll start filming next month, directed by Joel and Ethan Coen.

"It's a really great script. They adapted it from the book and the book is amazing, I'd never read it, but it's worth the read. I love Westerns, but I really love the Coen Brothers, so I'm looking forward to that, definitely."

The actor also spoke about the possibility of working with Steven Soderbergh on a pair of new projects: Contagion and a new biopic on the legendary performer Liberace.

"Contagion, Scott Burns who wrote The Informant! handed in this great script and it's timely, so it's more of an ensemble piece and I'm going to play a small part in that and then we're going to do Liberace sometime next year. None of (these movies) are actually lined-up like we're starting here and we have a green light. They're all things that I'm really excited about that are movable pieces depending on Steven's schedule. If this RFK thing goes then that might change. There's a play I really want to do. But they're all just really exciting things that are out there."

We reported on the Robert Kennedy project he mentioned earlier this week and Damon revealed that a script for the film is due next month.

Paul Greengrass' Green Zone stars Matt Damon, Greg Kinnear, Amy Ryan, Brendan Gleeson, Jason Isaacs, Khalid Abdalla and will hit theaters everywhere on March 12.