The way I see it, there are five major story beats in Jean's Dark Phoenix arc:
1. Starting in a happy life with friends, loving boyfriend, and fulfilling superhero career.
2. An unforeseen tragedy leaves her shaken and vulnerable. (Mystique's death, maybe?)
3. An opportunistic abuser exploits her vulnerability, hoping to control the Phoenix's power by controlling Jean. (Whatever name they give her, this is surely Jessica Chastain's villain.)
4. Jean shakes off the abuser's control, but the experience has given her a taste for indulging her dark side. She goes on a rampage, casually killing many. (Bye, Genosha.)
5. Her teammates manage to get through to her and reawaken Jean's mortal side. In horror at what she's done, Jean sacrifices herself* to stop the Phoenix from threatening the universe again.
If the film hits those beats, it might have a chance.
*Yes, Jean needs to die. They might do this the way the 90s cartoon did, with her resurrection happening like, a minute later**, but the film would be chopping its own legs off if it tried to do without Jean's death.
**That would also be a poor decision, of course, if not a crippling one. The proper time to resurrect Jean would be in a (more hypothetical now than it was during production) sequel.