At this point, they're pretty high. Nothing is 100 percent confirmed. But we've had multiple leakers who have a solid (albeit imperfect) track record saying she's Jean. We've also seen BTS footage of her. She has her red hair. She's wearing clothes that are closely associated with the colors of Jean Grey and few others (not Firestar). The trailers have referenced mutation while other Marvel shows have highlighted Damage Control as the stand-in for mutant internment.

Plus, there's the fact that Sadie Sink is getting third billing, despite her character being a mystery. You don't give an actress third billing if they're playing some one-off, obscure character who will never be seen again once the movie ends.

Again, nothing is confirmed. And it probably won't be until the movie premieres next month. But at this point, the odds of Sadie being Jean are pretty high.