A recent rumor claimed that Marvel Studios was planning several mutant-focused movies/shows in addition to the main X-Men reboot, and (supposed) details on some of these projects have begun to filter through.
We've heard that an Avengers vs. X-Men movie might be in the early planning stages (we assume this would be a massive end-of-phase event), and Daniel Richtman is now reporting that Kevin Feige is also interested in developing a Brotherhood of Mutants film.
If true, this could explain why Magneto is not expected to be a part of the X-Men reboot, as Erik Lehnsherr would (presumably) lead the team.
A version of the Brotherhood appeared in the original X-Men movie, with Magneto leading Mystique, Toad and Sabretooth. There have been numerous other members and leaders over the years in the comic books, including Pyro, Blob, Mastermind, Destiny, Quicksilver, and the Scarlet Witch (could there be a place in the group for Elizabeth Olsen's Wanda Maximoff, perhaps?)
There are quite a few X-Men related rumors doing the rounds online at the moment from various different sources, but we wouldn't put too much stock in them for the time being. Even if some or all are on the level, these projects are likely in the earliest stages of development, and are all subject to change.
That said, Marvel Studios shifting focus to the X-Men/mutants in the near future exactly be a major surprise, since Feige and co. will likely be looking for a way to refresh and rejuvenate the MCU after a series of disappointing Phase 5 entries, and what better way to do that than to add the Children of the Atom to the mix?
Feige assured fans that a reboot was in the works shortly after Disney acquired 20th Century Fox's assets back in 2019, but we haven't had a single official update until recently.
There were rumors that contractual issues may have been preventing Marvel Studios from introducing new actors as established mutant characters such as Wolverine, Cyclops, Storm, etc, to The MCU. It's said that if Marvel wanted to reboot the team using any of the same characters from Fox's franchise before 2025, the likes of Simon Kinberg, Bryan Singer and co. would be, at minimum, entitled to credits and compensation, and may even have some degree of creative control as well.
We have no idea if this is true, but it would explain why there's been radio silence on all things X-Men since 2019, and why the only established mutant characters we've seen in The MCU since is Professor Xavier in Doctor Strange in the Multiverse of Madness - with Sir Patrick Stewart reprising the role, and Kelsey Grammar as Beast in The Marvels' post-credits scene.
Hugh Jackman is also set to return as Logan for the upcoming Deadpool 3.
This wouldn't prohibit Marvel from debuting new mutant heroes and villains with no connection to the earlier films, however, which we saw when Kamala Khan was ret-conned as a mutant in the season finale of Ms. Marvel.