I suspect they're just going to dump the X-Men fully formed in the classic 90's Animated line-up--from the same alternate universe Rambeau ended up in--right into the audience's lap all at once . . . and then maybe kill them all off in Secret Wars or Doomsday or something, only to have a post credit scene with the "real" MCU incarnation of Charles & Erik and/or Logan, teasing their solo movie. Not sure what I base that suspicion on exactly; I could be wildly off-base.
I do find it weird that they're focusing so much on the legacy versions of the X-Men characters instead of introducing their own new versions of them first. It's been fun seeing them again, but it feels like kind of a weird way to bring the X-Men into the MCU, especially since they're not really introducing them, they're just showing up.Yeah -- it would be a little weird to bring back Patrick Stewart, then Kelsey Grammer, then Hugh Jackman, only to recast everyone else.