I wrote an article for my blog about this
Originally Posted by Optimus_Prime_
I wouldn't mind seeing them ape Terminator a little and do Cable vs. Nimrod returning from the future, maybe to stop Magneto from assassinating the President or something.
except instead of Nimrod I thought Apocalypse would be a cool choice. Apocalypse's mutant power would be time travel, and everything else he could do as far as super powers go would be genetic modification from future tech and weapons from the future
Also including cable would possibly alter history to undo the death of Jean Grey and Cyclops in X3 (I'm still sore about that)