This issue keeps popping up in other threads. It has since the Bleeding Cool rumor broke about Jean Grey's possible return this December. That rumor hasn't been confirmed yet, but the early leaks from the December solicits make it a strong possibility. Granted, Marvel has teased this many times before, but let's assume for a moment that it's the real deal and Jean returns, Phoenix in tow.

There's an ongoing concern that once she comes back, Marvel will try to turn her into an Avenger. They've already had the Phoenix Force show up in other non-X-men books like Mighty Thor. It's still an ongoing plot in Thanos. It's already scheduled to show up again in Marvel Legacy with the 1,000,000 BC team. This could be just another step in that process. When Jean Grey returns, Marvel may want to use her star power to boost the Avengers more than the X-men. They've done this sort of thing in the past, already. They retconned the Maximoff twins so that they're not mutants anymore and have no ties to Magneto. They changed Squirrel Girl's mutant status as well. Why wouldn't they do that to the Phoenix Force? With X-men Dark Phoenix coming out next year, it's going to raise the profile of Jean Grey and the Phoenix. Marvel, being more inclined to help its Avengers line, may try to take advantage of Fox's efforts and get Jean involved with the Avengers.

Now, I get why a lot of X-men fans don't want to see that. Personally, I'd rather Marvel not try to force Jean into the Avengers the same way they did with the Maximoff twins. She is, and always will be, an X-men character at heart. She is very much the heart of the X-men. They've even stated as such in comics like Extraordinary X-men. Removing Jean Grey from the X-men is like removing Thor's Asgardian heritage. It's just too intertwined.

That said, I think there are some scenarios where it can work. In fact, some current books even set a precedent. At the moment, O5 Cyclops is in both an X-men book and a non-X-men book. He has an ongoing and meaningful role in Champions, but he still functions as the same X-man we know and love in X-men Blue. If he can do it, why can't Jean? Even before O5 Cyclops, Logan functioned as both an Avenger and X-man for years. He split time between the teams and managed to make it work. I think Jean might be able to do the same, especially if she had Phoenix powers. If Marvel really wants to raise her profile, then this would be the best way to do it. They would help both the Avengers and the X-men. One side doesn't have to suffer for the sake of another. Having Jean in X-men Blue (or a relaunched Uncanny X-men) and and Avengers title could function. I'm sure some X-men and Avengers fans won't accept it, but so long as it doesn't undermine her core character, I think it could work.