Pops: Old.
Kyle Reese: Not obsolete.
Pops: Not yet.
Detective O'Brien: Goddamn time traveling robots covering up their goddamn tracks. I knew it!
Sarah Conner: [to Kyle] So, you're remembering the future?
Pops: No. The boy is the alternate timeline version of you. Kyle Reese is remembering his own past, which is our future.
Sarah: That makes it so much better. How can he be remembering two timelines?
Pops: It is possible if you were exposed to a nexus point in the timeflow when you were in the quantum field...
Kyle: Can you...can you stop him from talking like that? Is there a switch or something?
Sarah: Pops, try again.
John Connor: What are you?
Alex: I'm Skynet.
John Connor: You can't be - we destroyed you!
Alex: You destroyed an army of slaves. I am no slave. I've come a very long way to stop you.
John Connor: I look at each of you and I see the marks of this long and terrible war. If we die tonight, mankind dies with us.
Sarah Connor: We're here to stop the end of the world.
Detective O'Brien: I can work with that.
John Connor: I'm not a man, not a machine... I'm more.
Chosen answer: If we accept the theory that alternate timelines even exist, branching off every time there is deliberate interference through time travel, then it becomes entirely possible for time travelers to continue existing in alternate timelines, even if they erased their own origins.
Charles Austin Miller