Not that I'm anyone, but I have some Do's and Don'ts suggestions for future MCU X-men movies.
There's only one requirement: must incorporate the tension between mutants and non-mutants. It doesn't have to be front and center all the time, but it must be there in the background.
Strongly recommended:
* Leave out the school at first - maybe it's just me, but thinking back I don't think the school aspect has added all that much to the X-men movies, with the exception of XM2 and maybe First Class.
* De-emphasis/reimagining of Professor X and Magneto - I wouldn't be opposed to not introducing them at all for a while. In particular I wouldn't make them the de facto leaders of the opposing mutant factions from the start; new stories should have them rise up the ranks of the mutants.
Magneto's backstory needs rewriting: don't make him a direct survivor of the Holocaust, it ties the universe down too much. Next year will make it 75 years since the end of World War 2. That's about as far in the past as the end of the US Civil War was at the start of WW2. I would like to see the X-men be born of our contemporary world and its issues rather than those of a now-distant past.
* Incorporate the space aspects, but judiciously - full disclosure, I came to the X-men through the movies, so it was a real shock when I started looking at actual X-men comics (I was like Shi'ar Empire, WTF, haha) Obviously they cut all that out for the Fox movies, but the time is right to reintroduce it: MCU has successfully done the heavy lifting of establishing a universe beyond Earth, and I would hope a major theme of post-Endgame movies is humanity's reaction to aliens. This would add a nice new dimension to the mutant-human conflict. But I would not make the X-men akin to Guardians of the Galaxy.
This final one I have no real argument for except a gut feeling: contrary to some other opinions here, I would not reintroduce the X-men universe by way of a TV series. Maybe it's a reaction to the uneven quality of the Star Trek movies (not too bad for TOS, very uneven for TNG). Story wise it shouldn't be a problem, but my prediction is making X-men on TV first will hinder, not help, future box office.