But remember, they destroyed all the things needed to make Skynet's coming about at the end of T2, (the original arm from T1 and the chip from T1) so basically, the rebellion in 1997 and indeed the T3 film can't really happen. Destroying all the stuff needed by Skynet would mean that it could have never have been made, and so it would have been instantly eliminated in the future, so everything that happened since 1997 would have become undone, and Skynet could not possibly send another Terminator back, as it dosn't exist.
The arm Arnie lost in T2 at the end can't be used to start it all off again, T2 was only because they found the chip from T1 AND the arm. There were no more chips left after T2, they destroyed them all, and there are no chip's inside Arnie's arm. So with no chip, and no recorRAB of how Cyberdyne started experimented on the original chip, the finders of the arm would have nothing.
I'd love to see the excuse they give on how the humans screw up and make the rebellion happen.
Plus, if they stop Skynet from coming about, John Connor would have no reason to send Kyle back in time, Kyle then wouldn't have found Sarah, wouldn't have had sex with her, so John wouldn't have been born, Sarah wouldn't be a 'nut' because the Terminator wouldn't have come back trying to kill her, and all those people from 1984 would be alive again, including the other two Sarah Connor's.
Personally, I hate what they have done to the Terminator. They done exactly to T2 what they did to RoboCop 2. Cash in on the original by making it an all out shoot 'em up flashy special effects gun gallery. If they had have kept the original tone and style to the first, the sequels would have been far better. They were still a success because of the hype they both generated, but they could have been so much more.
I wonder how much money Cameron, (or whoever is directing this one), has spent on effects... $150 million, $200 million...?