[Just to be clear: I have not watched X-Men: Apocalypse yet and this post will contain zero spoilers as a result.]
On the one hand I don't think I can really complain about Jennifer Lawrence wanting to do more X-Men movies. She's a fantastic actress and hopefully her future appearances will lean more towards the First Class than the Days of Future Past. So, definitely something to cautiously look forward to.
On the other hand, though, Fox's X-Men movies have a tendency towards mediocrity, a horrible “oh, just get it made” attitude that squandered the promise of the First Class reboot in the very next film. Until now everyone has been assuming that Fox's plan was to keep turning out X-Men films until Hugh Jackman ages out of the part, quits or dies and we were all sort of okay with that. There have been a few genuinely great movies in the franchise. It doesn't break anywhere near even on the good/bad divide but there have been good ones.
I'm not going to lie, I want to see Marvel and Fox come to a Spider-Man style shared custody deal and the one thing standing in the way of that until now was Hugh Jackman, a middle-aged man. Now Fox has Jennifer Lawrence's star power to rely on into the future and she's twenty years younger than him.
Then again, this is Hollywood we're talking about so she probably "counts" as being the same age as Jackman so the overall plan might remain unchanged.