The original is such a perfect example of a 'plausible' and consistent time travel story that my only concern would be any holes that might arise from changing things too much. Still, the writers are no doubt absolutely aware of that and will try to ensure that consistency remains.
My memory's failing me, can anyone else think of time travel films that were similarly tight in logic and execution? The Terminator is about the only one I can recall right now (and of course that went out the window with the follow-ups).