^ I don't see them turning Gambit into a Cable-esque time traveler, which means whatever timeline they start him in that that is where he will likely stay.
If (and when - IMO) he is in Apocalypse that will likely be it, he'll be relegated to the past.
That doesn't mean that someday they couldn't have a present timeline movie that includes an aged Gambit, but that's less likely then them churning out one, two, or more Gambit solo films set in the past...
I think everyone needs to come to grips with the fact that the focus of the X-Men is now on the past. This Apocalypse movie is, i believe, going to be (in many ways) both a close to the First Class "trilogy", and a start of the future focus of the X-Men. Us getting to see these young versions of the X-Men grow and develop over the next decade makes so much sense. So if they are focusing on these characters in the 80's and possibly 90's, then it's hard to believe that they will ever come out with a present timeline X-Men film that would include the OT cast.
Look, that trilogy is done. We've been left with the happy future that many wanted to see. And although there are many good characters (as well as actors and actresses) in the OT movies, the truth is that their time is pretty much done. Again, the obvious focus is the younger, fresh x-men from the mid-80's!!!
So if they are going to put Gambit somewhere as an X-Man, it just makes sense that that is where it will be.
Yes, this hurts some fans. It hurts me that the Rogue and Gambit relationship won't happen, but I accepted that the moment Bobby gave her the ice rose. They effectively replaced Gambit, in that relationship, with Bobby. Fine, moving on...
At the same time it hurts me that Iceman will never be a member of the "first class", and that Storm will be, but again, it is what it is. Moving on...
It bothers me that we'll never get the Giant Sized X-Men number one, but again, this x-Movieverse is not the comics.
Logically people just need to accept that the focus is going to be, going forward, on this young cast. And if that's the case then that is where gambit will be. Even so, they can do so much with him and I believe he can absolutely work in a film with McAvoy's Professor x, Fassbender's Magneto, Lawrence's Mystique (if she continues in the role), Hoult's Beast, and whatever younger X-Men we get in Apocalypse and any future X-movies!
Oh, I will say that I do believe there are a couple of ways that we might see the OT cast again.
One is a new spin-off series (possibly a trilogy or even a tv series) that turns the OT cast into a different group. For example, it wouldn't be too difficult to turn Kitty, Colossus, Iceman and Rogue into Excalibur. Add in other characters, like Captain Britain (I argue that he would be shared), Meagan, OT Nightcrawler, and/or Pete Wisdom, and you could have something interesting, set in the present!
The next is a Cable origin movie that would almost have to include Famke and Marsden. This could lead to X-Force, but with Cable being a timetraveler that team could be in the past or the present (or any time inbetween).
Lastly is a cross-over movie with the Fantastic Four. Once the FF movie bombs (I'm speculating) they will be forced to do something that could save the franchise. By combining the OT X-Men cast (at least some of them) with the FF in a cross-over story, it would get a lot of hype!