I don't see how it's a dead end.
For me I was excited to see the standard x-men team in Apocalypse, it was basically the best aspect of the movie, and I felt like "good, finally we can get back to the x-men". I want to see what's next for them.
Currently I'm not clear on whether the characters we see in Apocalypse HAVE to have a future that ends them up exactly where we see Wolverine find them happy and alive at the end of DOFP, OR, if they have an unknown future.
If it's an unknown future not bound to that, then, they are good to go, and don't need this Cable story I'm about to suggest below.
But, if it is bound to that, which I feel it is, then that's a big restriction to the possible storylines, plus you would have the weirdness of the time catching up and seeing that, for example, Jean doesn't look like Famke Jensen. (It also meant that I knew nobody was going to die in Apocalypse, because they can't...)
I think the solution is for the next X-men movie to have Cable in it. The way it would go is that at the end of DOFP, in the history of those people that we see happy and alive at the school, 20 years ago Cable did NOT show up from a time portal from the future.
BUT, in the next x-men movie with the new young cast, Cable Does show up from the future, thus creating a new branch time line. It can be quickly and easily explained by Cable and/or Xavier. That might mean that the x-men movies are using both the LOST type of time travel and the Back To The Future type of time travel at the same time, but, hey, they do that in the star trek franchise and it's ok.
X7: So how about it's still the cold war, 1988, and Cable comes back from an alternate future where the Soviets cause some terrible, possibly anti-mutant, future, with Omega Red involved. Colossus can be introduced. Stuff happens in the movie that finally makes Magneto and Mystique become bad guys. They also do something that makes it so the horrible long Soviet future doesn't happen and the cold war will end just like it did in real life, maybe the berlin wall comes down / is referenced in the movie after Omega Red is defeated.
X8: Then in the next movie, it's roughly 1993, grunge and Nirvana lol, we meet Rogue who is under Mystique's wing, and then some kind of new alien superhero character made just for this movie gets drained by Rogue and she gains her superpowers and joins the X-men. The plot mainly has the x-men fighting the brotherhood. Probably Quicksilver joins his dad. Maybe introduce a good version of Juggernaut. Merge Gambit at the end to meet Rogue if that works, I dunno about the Gambit movie.
X9: The final movie, in roughly 1999, is about Asteroid M, and a little bit of aliens (possibly they are looking for the alien superhero that Rogue put in a coma) and the Phoenix. Then at the end of the movie when everything is back to normal, Wolverine shows up at the school and symbolically brings us back full circle to X-men 2000. 
Future: Any future movies would skip the time during X-men, X2 and Last Stand (that time period, regardless of timeline lol) and start after that, which I guess is what, X-force or whatever.