Originally Posted by Legion
I'm betting that this film will borrow elements from X-Men TAS episodes "One Man's Worth". The time traveler from the apocalyptic future will travel to the "present" (Between X2 and X3) to recruit the X-Men to their cause.
I'd also like to see Rachel Summers as the time traveler. I think it would create a lot of speculation as how she came to exist. At the climax of the film the phoenix force can emerge and the X-Men wonder how to handle the threat..
That's a possibility. It then means, of course, that the time traveller and the present-day X-Men will then need to travel back to the 60s. That double time-jump could work. But remember that if it's between the events of X2 and X3, then Jean Grey is apparently dead (in fact, cocooned beneath Alkali Lake).