According to my scenario,
the First Class-Apocalypse-Deadpool-Logan Timeline is the
third one, not the second one as everyone thinks.
The X-Men timeline was altered EVEN before the events of DOFP.
The X-Men timeline morphed
TWO TIMES, not just one.
This theory explains all incongruences and errors, and also fixes them once and for all.
No Father/Son crap, no similar mutants crap, no ignoring timestamps.
For more details:
http://x-continuity.blogspot.com
I cannot conceive that the "Logan" dystopian future is the end of the saga. That would ruin my enjoyment of X-Men 7, X-Men 8 or any other movie set in the past.
So my guess is:
Laura/X-23, once adult, will travel back in time and
change history again. The events of "Logan" will be erased. There will be a fourth timeline, I guess.