This one is filed under large rumor. Whatsplaying has some "third hand" info that links former Governor Arnold Schwarzenegger, with a return to the Terminator franchise. Recently producer Gale Anne Hurd [Terminator, Terminator 2, Aliens] stated she would "love" to make another Terminator movie. Hurd of course has worked with Schwarzenegger before on the first two Terminator films. Whatsplaying states: Schwarzenegger is to "play multiple characters in a new Terminator movie, playing both the human who lent his likeness to the Terminator as well ‘hundreds’ of Terminators".
This seems rather unlikely especially when EW recently spoke to director Ivan Reitman and the director stated that Schwarzenegger was unlikely to return full-time to movies. But at the same time its not exactly out of the question especially since Schwarzenegger is interested in getting back into acting and the roles that are out there for him at this point in his career are pretty finite outside of comedy.