SPOILER WARNING: This article contains major spoilers for X-Men Blue #27’s “Countdown to Extermination” by Ed Brisson, Oscar Bazaldua, Erick Arciniega and Joe Caramagna, on sale now.
Marvel's latest Extermination post-credits scene continues the X-Men's struggle 20 years into the future, as they battle an army of Sentinels at the site of the Xavier Institute for Mutant Education and Outreach. With this being the future, our time-displaced, original X-Men are now adults rather than the teenagers we've been following for the past several years. What's more, they're leading a new generation of students alongside Kitty Pryde, who appears to have taken on Professor X's role as the headmaster of the institute.
Jean Grey does her best to keep the kids calm, but Cyclops doesn't believe any place is safe -- whether or not the Sentinels are the main threat remains to be seen. However, Angel is quick to point out that none of this would be happening if they had simply gone back to their original timeline.
For context, Marvel recently resolved the time paradox that's kept the original, younger X-Men from returning home. Cyclops, Jean Grey, Beast, Iceman and Angel were destined to go back in time for good, but something must have happened between now and 20 years into the future that's caused them to either remain stuck in time.
Sadly, before Beast can refute Angel's statement, he's cut down by an energy blast from a Sentinel.
Of course, the death of a character in the future doesn't necessarily impact the present, but it still displays the type of dire situation the X-Men have found themselves in. Also worth noting is Beast's physical appearance has undergone another transformation; the future has seen him fully adopt his mystical look with protruding horns and grey fur.
There is still not a lot known regarding the X-Men's Extermination event, except for its initial teaser image featuring the classic X-Men team apparently re-merging with their time-displaced X-Men Blue counterparts. Perhaps whoever survives the Sentinel attack decides to travel back in time to meet their younger selves, in an attempt to either change the timeline or force the X-Men back to when they belong.
However, we also need to keep in mind the ominous text that accompanied the Extermination teaser: “Exterminate the past. Eliminate the future.” If the older X-Men are traveling through time to change the past, it doesn't sound like their goal is to simply ask nicely for things to go back to the way they were.