Now that the deal is close to being finalized, let me say that these are my casting choices
Matthew McConaughey - Reed Richards/Mister Fantastic
Emily Blunt - Susan Richards/Invisible Woman
Seth Rogan - Ben Grimm/Thing
Sergej Trifunovic - Victor Von Doom/Doctor Doom
Bella Thorne - Jean Grey/Phoenix
Hunter Page-Lochard - Lucas Bishop
Oded Fehr - Erik Lensherr/Magneto
Madison Davenport - Kitty Pryde/Shadowcat
Jamie Clayton - Raven Darkholme/Mystique
Stephen Lang - Nathan Summers/Cable
Emile Hirsch - James Logan Howlett/Wolverine
Diego Luna - Julio Richter/Rictor
Pierce Brosnan - Tom Cassady/Black Tom
Lady Gaga - Alison Blaire/Dazzler
John Cena - Cain Marko/Juggernaut
Terry Crews - En Sabah Nur/Juggernaut
Elizabeth Tan - Elizabeth Braddock/Psylocke
Mahershala Ali - Norrin Radd/Silver Surfer
Hugh Grant - Nathaniel Essex/Sinister
Eva Green - Neena Thurman/Domino
George Corpsegrinder Fisher (voice) - Annihilus
Ryan Gosling - Warren Worthington/Archangel
Neil Patrick Harris - Shatterstar
Michael Spears - (Name Classified)/Forge
Viva Bianca - Emma Frost/White Queen
Jean Claude Van Damme - Charlie Cluster/Fantomex
Vasily Stepanov - Arkady Gregorovich Rossovich/Omega Red
Til Schweiger - Christoph Nord/Maverick
Daniel Tosh - Jamie Madrox/Multiple Man
Siorise Ronan - Theresa Cassady/Siryn
Finn Balor - Victor Creed/Sabretooth
Sasha Grey - Seline Galio
And keep Ryan Reynolds as Deadpool
I'm not sure who I want for Cyclops, Beast, Havok, Strong Guy, Polaris, Omega Sentinel, Nightcrawler, Colossus, Rogue, Gambit, Daken, Xavier, Storm, Warpath or Human Torch but I feel like a lot of them should be unknowns since they should search for younger actors to play them. I'm completely in favor of somebody from Nollywood or Wakaliwood playing Storm since she needs to be play be an African and I want an actor from Russia to play Colossus. Warpath last time was played by an Asian-American actor but this time around, I feel like he really needs to be played by a Native American actor. With Xavier, I'm all for changing his race since Xavier's entire worldview and motivations are so grounded in African-American culture that it doesn't really make much sense for him to be white. Rogue and Nightcrawler and Mystique's children so they're required to be young and Gambit is Rogue's love interest so he also needs to be young as well. Same goes doubly for Havok since he's Cyclop's younger brother and Polaris as Havok's love interest. Beast is the other character I'm comfortable with having a race change since his love of two-dollar words is something which black nerds do more than white nerds. Strong Guy just needs to be an Italian-American body builder who can also do comedy. That pretty much requires an unknown. I really want somebody from Bollywood to be Omega Sentinel as well.
As for the New Mutants/Generation X/New X-Men characters, I'd get unknowns to play them since I want them to be really, really young and to introduce them on their own TV spin-off where the first class will be Sunspot, Mirage, Cannonball, Meltdown, Wolfsbane, Karma, Skids, Magik, Warlock, Cypher and Magma. After a season or two, we'll get some underclassmen introduced with Jubilee, Skin, Synch, Husk, M, Chamber, Hollow, Mondo and Gaia. And once that second class' cast is about to grow up and be transferred to the X-Men, X-Force or X-Factor films/shows, I'd do a third class with Dust, Hellion, X-23, Rockslide, Surge, Wind Dancer, Prodigy, Elixer, Ink, Mercury, DJ, Match, Trance Pixie, Shark Girl, Nature Girl, Tempus, Hijack, Goldballs, Whither, Anole, Gentle, Bling, Blindfold, Loa, Icarus and Tag. (A huge part of this cast would naturally die so it can afford to be big.) This show MUST be on Disney+ as doing it in-house is the only way to afford the budget to introduce Warlock and Rockslide on the show. And the New Mutants would team up with the Power Pack, Champions and Ms. Marvel. Maggot won't be part of the second class since NOBODY liked him. This cast is way too young to think about casting anyone since they'll have aged out of the role by the time it comes to casting them.