Well, that's one way to get around your aging cyborg. Reboot the whole thing. A press release sent to Deadline from Paramount - who'll be distributing - has announced that the new Terminator, set for June 26th, 2015 and starring Arnold Schwarzenegger as the Terminator, is part of a stand-alone trilogy and a reboot.
Another interesting factoid added by Deadline is that the rights to Terminator will eventually revert back to James Cameron in 2019, who has yet to be satisfied with any of the follow-ups and spin-offs that came after his two films. So they're hauling ass to make three movies before that happens. Always a recipe for a quality product.
Aint It Cool News recently ran some wild speculation that the Rock would be in it and it'd be set in the '40s, none of which passes my BS detector. But if they must reboot, a shakeup on that level is probably what's needed, as I don't need to see a Kyle Reese/Sarah Connor romance again.