No idea why they are taking so long to reboot the Xmen in the Marvel Universe.
Given how poorly whichever "Phase" this is of the MCU, I wish they'd just reboot the whole thing. All the original actors are done, you've started doing all the time travel/multiverse nonsense that's driven off a lot of the casual fans that weren't comic fanatics, all the original franchises are ending or doing soft reboots with new versions of the characters... It feels like it's run its course, and fans are making that clear by handing you your first financial failures.
Plus, you got the Fox properties back, the only character you don't own is Spider-Man, but Sony seems amenable to let you prolong their license for them. So you've finally got your whole universe to play with. Use the Kang story to give the MCU a fitting send-off and start over.
Start with the Fox properties because they've already been on hiatus for a while. In a world just like ours, mutants with powers start popping up. So you've got a modern "racial" crisis to parallel all the other divides we've got today. That's your X-Men story to kick things off.
So then it's about people with powers. How do we compete? Can we work with them? Can we control them? That's your Fantastic Four story. Scientists led by Victor von Doom try to figure out how to get powers, an experiment goes wrong, VvD gets muffed up, four others get powers. Boom, done.
Then the government gets into the race for powers and have one failure (Hulk) and one success (Cap). Then an engineer sees all this going on and it freaks him out, so he makes a suit of armor. Then the gods get miffed that humans are playing with forces they shouldn't be, and the secret mystical world has to come out of the shadows to protect folks for similar reasons, and so on and so on.
A grounded, relatable, connected launch to the whole thing, spread over a few years, being careful to put as much distance between the last versions and the new ones. Avoid the mindscrew (and wildly unnecessary) time travel and multiverse stuff to keep the stories accessible, take your time forming the teams and doing the crossovers...
It just seems like an obvious point to begin again given how overcooked and disappointing so much of the MCU has been lately. Why launch these new ideas into a waning universe when you can use them to start a new one?