From what I can tell, this trailer has revealed the full plot. Looks like the original (Arnold) T-800 goes even further into the past than the original film (or sequels), where he befriends a younger Sarah Connor and raises her from childhood. By the time Kyle Reese shows up it ain't the 1984 he and John Connor expect. Old terminator corrupted the timeline resulting in an alternate timeline. I'm just not feeling this. Might have been cooler if they'd gotten Robert Patrick or Michael Biehn back.