^ Why does every single person who brings up this idea not realize one simple truth? Any creation of a ST'09-style alt timeline scenario will invalidate The Wolverine, which is not something FOX would let Singer do even if he wanted to.
The reason? It's not good business to release a movie - standalone though its story might be - have audiences pay to see said movie, then turn around a year later and say 'you remember that movie we released last year?' It happened in a completely different universe'.
There will obviously be two timelines involved. The question is, which one becomes invalidated, if any? You basically have three camps:
1. Fans that believe that the OT events will be invalidated such that Scott, Jean, and Professor will return in the corrected timeline for future sequels featuring these characters.
Evidence for: Singer's interview. The question was directed at TLS particularly. Singer said he will fix things, and these changes will make fans happy. We can only assume he was referring to the unfortunate circumstances we were left with after TLS.
Evidence against: Invalidating TLS while preserving X1 and X2 is mutually exclusive for the simple fact that everything in the trilogy led up to X3. It would also invalidate The Wolverine. It would completely undermine the franchise.
2. Fans that believe this is an alternate future following TLS.
Evidence for: It has been said this is an alternate future as is. Most of the returning characters are survivors from TLS. There are viable explanations to bring back Xavier and Magneto.
Evidence against: Not much. We know the trigger point is 1973. What happens between TLS and DoFP (Future timeline) is anyone's guess. Somehow, Sentinels surfaced and the mutant race is on the brink. There also seemed to be a greater sense of unity between humans and mutants at the end of TLS, so how did this future even come about?
3. Two concurrent timelines
Evidence for: If DoFP is an alternate universe, then the OT is as well. Nothing can be done to change the fates of these worlds as they are two separate universes. The only way this happens is to preserve the events of OT. So time travel would create two universes branching off from 1973 but both timelines still exist parallel to one another.
Evidence against: Paradoxes that make your head spin and are impossible to work around.
