All the ending was saying to me,is that what they showed you in 2023 is the only thing they can be held accountable for,from this point forward,in terms of accuracy.....In the sense that Jean,Cyclops,Storm will all be around the same age,Rogue will be younger than them...But NOT that any of the other movies still mattered....I thought directors themselves said the movie was made specifically so that they cant be held accountable for innacuracies in timeline they are starting....you cant really watch the movies in order and have them make sense,so they are eseentially telling you none of the x1-3 shyt happened....And that the events from First Class and DOFP only kindve happened the way they were shown,I say kindve because they might want to have a loophole where they bring back characters who they said were killed off in dofp,down the line.
Kinberg has explained it. The timeline has changed and the characters and events that happen in the first flick could still happen but they'd happen differently because the characters are different now since they've messed with the timestream