Chris Claremont's X-Men Forever #5 was the conclusion to his first X-Men Forever story arc (though, as Claremont is wont to do, it does not really feel like much of a conclusion). X-Men Forever picks up exactly where Claremont left off in 1991 with X-Men 3, pretending nothing every happened in the meantime -- sort of.
Obviously a lot happened in the intervening 17 years, but a lot of folks claimed -- in a bit of an exaggeration -- that Morrison was the first person to make them exciting again in his high profile New X-Men run. (I myself was always a big fan of the four month alternate universe Age of Apocalypse, but that may have just been because I was too young to know better). In a search for a successor, Marvel went to Joss Whedon to pick up where Morrison left off. In a much less high profile movie Warren Ellis picked up Whedon with a little story called "Ghost Boxes," about parallel universe invading -- the whole thing was mostly forgettable, as to my eye it looked like Ellis had this story in a drawer, and sort of shoehorned the X-Men into it. And in the larger Marvel Universe Wolverine became one of the most ubiquitous characters in comics, on both the Avengers, X-Men, and X-Force (as well as his solo title) and has two "kids" with similar claw powers as well.
Claremont is going to pretend all this -- and more -- never happened in his X-Men Forever run, except I feel him responding to these writers everywhere, making his run more like Ultimate X-Men: a riff on what we know happened in mainstream continuity.
In mainstream continuity Wolverine is ubiquitous. In X-Men Forever he is killed almost immediately, (on a book that is surely going to be flirting with cancellation since it is for such a niche audience, so many comic book readers not being able to read when X-Men 3 came out).
In mainstream continuity Wolverine has a daughter who has two claws instead of Wolverine's 3. In X-Men Forever Kitty Pryde (who always had a kind of daughter-father relationship with Wolverine anyway) literally gets one of his claws.
In mainstream continuity Storm (in Warren Ellis's run) decided she was fine with being a killer -- actually signed off on genocide. In X-Men forever Storm is split into two people at least one of which looks to be a killer, the other an innocent.
In mainstream continuity Psylock turned out to be two people: the new Ninja Psylock was installed and then out of nowhere, the old version reappears. (I don't remember how all that got resolved, or what started it in the first place). In X-Men Forever de-aged Storm, thought to have become the new one, turns out to be a separate person as well.
In Claremont's original run there is a famous image of Wolverine in the sewers of the Hellfire club saying "now its my turn." Whedon revised this image by putting Shadowcat in this same pose and situation. In X-Men Forever, Claremont sort of tries to bring it back by having Sabertooth reenact the same pose with a similar line, while at the same time having Shadowcat takes Wolverine's place in another way with this new claw.
Morrison's first story really played hard into the Mutants are the next step of evolution, and went so far as to say humanity was dying off due to a genetic trigger. In X-Men Forever, Claremont reverses this suddenly declaring that mutants are NOT the next step in evolution and are dying out do to a similar kind of internal trigger, burning out young because of their powers (The explanation does not make a lot of sense to me as it is based on the argument that there are no mutants over 60, but this seems to be more that mutants are a sort of recent development).
X-Men stories have played around with alternate time-lines, timelines that were eventually reset. Claremont's title is set in a kind of pocket-continuity, but you get the feeling he is figuring everyone else's stories as continuity to be reset so the universe can be put back the way it should have been, just as it was in Age of Apocalypse and Here Comes Tomorrow.