Originally Posted by Lightning Strykez!
We've waited long enough dammit.
Well, let's think about it for moment.
If the dystopian future is after X3, it can't have Jean, Scott (and possibly not Xavier). But if that timeline is then erased or altered by the time traveller(s) stopping the trigger event, then we can have Famke/Jean and James/Scott back again at the end of the movie.
The baffling thing at the moment is that Patrick Stewart's Xavier is in DoFP. This probably means one of these options:
a) The DoFP future is after X3 and they are using Ratner's post-credits scene showing the mind-switch into a braindead twin
b) The DoFP future is after X3 and they have found some other explanation for how Xavier is still alive when we saw him explode. Or maybe he is physically dead and just exists on the astral plane, who knows!?
c) The DoFP future is an alternate future where Xavier didn't die (and so maybe Jean and Scott didn't die either!). This future may be erased or altered by the time travel, with some people suggesting the altered timeline turns into what we saw in the original trilogy.
It's all a bit brain-frying, but those seem to be the options.
It's difficult to tell until we hear if Halle, Famke or James have been cast.