There's still a whole lot we don't know for certain about the upcoming Terminator 5, otherwise known as Terminator (2015). However, Arnold Schwarzenegger is confirmed to reprise as the titular killing machine (even though he's now 66 years old), drawing from a screenplay written by Laeta Kalogridis (Shutter Island) and Patrick Lussier (Drive Angry) that will reboot the sci-fi franchise's convoluted timeline, in order to setup for a potential new stand-alone movie trilogy.
Alan Taylor has left news of him directing the film as "rumor" for the time being, though that hasn't prevented the Thor: The Dark World helmer from saying that - in the purely-hypothetical situation that he were to wind up directing the Terminator reboot - he would emulate Christopher Nolan's approach with Batman Begins, where it concerns resetting and contemporizing the IP created by James Cameron some 30 years ago.
The rumored storyline for the fifth Terminator installment resembles the premise for the upcoming time-travel superhero movie, X-Men: Days of Future Past, as the adult John Connor (who Taylor wants Tom Hardy to play) in the dystopian future sends a deadly robot (Schwarzenegger) back in time to protect his mother Sarah - when she was a 20-something individual - and prevent any timeline alteration that would destroy humanity's last shred of hope in a 21st-century war against rogue artificial intelligence machines.
So, in essence, it'll borrow and blend plot/character elements from the 1984 Terminator and its sequel, Judgement Day.
Margot Robbie (The Wolf of Wall Street) was previously listed among the actresses in contention to play Sarah Connor in the Terminator reboot, but Deadline says the race is now down to Brie Larson and Emilia Clarke. The former has enjoyed a strong year on the indie movie circuit (with roles in Short Term 12 and The Spectacular Now), but the latter is said to have the edge - partly, of course, because she collaborated with Taylor before on HBO's Game of Thrones TV series.
Both Clarke and Larson are renowned for their ability to portray determined and occasionally fierce, yet also vulnerable and overall multi-dimensional women onscreen; though, Clarke has more experience at play emotionally-grounded characters in serious fantastical genre fare, while Larson has a stronger background in comedy (see: 21 Jump Street, Don Jon). Moreover, both actresses are near the same age as Linda Hamilton when she played Sarah Connor in the mid-1980s, so that might be a clue with regard to when the past sections of the reboot will take place.
As it were, Kalogridis has worked alongside Cameron in the past on Avatar and his on-hold Battle Angel adaptation. Couple that with the emphasis on casting the Sarah Connor role and the involvement of producer Megan Ellison (Her, American Hustle) - whose Annapurna Pictures banner owns the rights to the Terminator franchise currently - and it stands to reason that the upcoming reboot will return the franchise to its feminist roots, after the third and fourth movies strayed a little ways from that outlook.
Indeed, the last two films - Terminator 3: Rise of the Machines and Terminator Salvation - have their strengths, but were so lackluster overall that it might be preferable to just start the entire continuity over from scratch, rather than continuing marching forward - especially, since the possibly of a post-Judgement Day trilogy kicked off by Salvation didn't come to fruition. (To mention nothing of more time-travel confusion introduced by the Sarah Connor Chronicles TV series).
With a sci-fi writer (Kalogridis) and horror specialist (Lussier) on scriptwriting duties, bringing the Terminator series back to its genre beginnings appears to be very much the plan with the fifth installment/reboot. Plus, given what Taylor has said to date, it sounds as though he intends to bring more of that Game of Thrones grit and political intrigue to the Terminator franchise, compared to his vision of Marvel's Thor universe (which, after all was said and done, was more of a Star Wars-like fun serial adventure than anything else).
Terminator 5/Terminator (2015) will open in theaters on July 1st, 2015.