A fifth (and maybe sixth) installment in the Terminator series seemed like a questionable notion, until maverick producer Megan Ellison (who helped produce True Grit) won a bidding war for the film rights. Since then, we've been cautiously optimistic — but the next Terminator sequel keeps having setbacks.

First Arnold Schwarzenegger's highly publicized personal problems forced him to put all his projects on hold. And now director Justin Lin, who's helmed a few Fast & Furious films, has bowed out of directing Terminator 5, because he needs to focus on Fast & Furious 6. (But according to one account, Lin may be able to come back to the Terminator project, if the producers can wait until after he finishes F&F6.)

Ellison and company want to put the first of two Terminator films in production by the end of 2012, and there's a ticking clock involved. The North American Terminator rights revert to original director James Cameron in 2018, and Cameron's not expected to approve any more films in the series. So the next two Terminator films, if they even happen, are likely to end the series once and for all.

There is one bit of good news, though — according to one report, Schwarzenegger managed to coax his friend Cameron to come to one or two "brainstorming sessions" about the project, so there may be a bit of Cameron's actual input this time around. [Deadline and The Wrap]