“The Terminator” is coming back, but will Arnold Schwarzenegger?

After a year in the development shop, “Terminator 4” is ready to be mobilized for a 2005 production start. “Terminator 3: Rise of the Machines” scribes John Brancato and Michael Ferris have completed a draft of a script that was developed under the supervision of “T3” director Jonathan Mostow.

C2 partners Mario Kassar and Andy Vajna are returning as producers, and “T3” financier Intermedia, which has underwritten development so far, will begin the process of setting up the coin for the picture. Company topper Moritz Borman is expected to engage the studios and distributors that bankrolled “T3.”

Mostow, who took over the “Terminator” franchise from James Cameron, is expected to next direct an untitled thriller he scripted for Paramount. Intermedia will open formal negotiations shortly for a deal that would make “T4” Mostow’s next directing job.

Schwarzenegger’s availability is the big question mark, since he’s engaged as governor of California. Discussions have already occurred for him to return for an encore, but the likelihood is that it would be in a limited role. Sources said the expectation is that “T4” will break in a new terminator model.

Intermedia will be meeting soon with Warner Bros., which distributed the film domestically, and Sony Pictures, which bought most of the international rights. Both of those studios have an option to serve the same roles in the fourth film. The film worked out nicely for both studios: The $175 million-budgeted pic grossed around $430 million worldwide. Distributors in other territories like Japan-based Toha Towa, will also get first crack at a reprise.

“T4” hasn’t been formally budgeted, but the next film isn’t expected to cost as much as the last. For one thing, advances in f/x technology should make shots more economical. There is also the removal of a $30 million line expenditure, which was Schwarzenegger’s record-breaking upfront salary for “T3.”

There is no word on whether Nick Stahl or Claire Danes has yet been approached for returns. Neither is believed to have been signed to an option agreement.