I thought I'd start a new thread on this issue since it seems to come up in bits and pieces every now and then. As it stands, the O5 X-men have been in the future for nearly five years worth of comics. They arrived in 2012 under Bendis and have undergone a lot of changes, shake-ups, and what not in the process. Their original reason for coming was based on adult Cyclops killing Xavier and Jean being dead. Well, Charles Xavier is coming back. Jean Grey is coming back. At some point, adult Cyclops will come back as well. Even before that, though, I think it's safe to say that the O5's original premise for coming to the future is somewhat obsolete. So I think it's worth discussing how their presence will eventually be resolved.
I start this thread with the full knowledge that Cullen Bunn recently said that the upcoming "Cross Time Capers" arc in X-men Blue will directly address that issue, to some extent. I imagine it'll generate plenty of other discussions, moving forward. But we do know that the O5 are sticking around after Jean Grey returns. They'll likely be around once Xavier returns in Astonishing as well. So what's the ultimate endgame here? What will Marvel do to bridge the gap between the O5 and their adult selves?
Personally, I believe that at some point, the O5 X-men are going to either merge or "become" their older selves. I put "become" quotes because there may be some sort of time travel or magic retcon involved in that process. The entire premise of the O5 coming to the future in the first place was to explore the early X-men, minus all the baggage they've accumulated over the past 50 years. Well, perhaps this is how Marvel streamlines these characters, mitigating the baggage while making their actions in the future count.
For Iceman, that means becoming more comfortable with his sexuality, which his adult self is still struggling with.
For Angel, that means taking on a form that isn't always at the mercy of Archangel.
For Beast, that means either remaining less "beast-like" or giving his older self some much-needed cleansing from all his misguided sentiments.
For Jean, that means her older self can learn the lessons of her younger self, thereby helping her avoid the mistakes that got her killed twice.
For Cyclops, and this is probably most pressing, it means becoming an adult Cyclops that lacks the baggage, bad decisions, and burdens that his older self accumulated.
It seems like the cleanest possible outcome, which is why I doubt Marvel will go this route. But I think the goal is to make the O5's presence in the future count for something that impacts the entire timeline. That's just my theory though. I'm sure many others on this board have theories and sentiments of their own on this issue. This is the place to share and discuss.