Hickman doesn't need to stay long to left an impression. He could just leave the seeds for other writters to pick up.
Going by the page panels, it looks like "The most important scene in X-Men history" will be summed up in a few words. Something succinct and #hashtagable for marketing.
Top Panel: Charles asking Moira for the truth, whatever that is.
Second Panel: Moira drops the BIG REVEAL, probably a quick phrase - "No more mutants"-style. (I'm guessing something like "Mutants didn't start on Earth" or "Mutants aren't from here"... maybe something retconning her into knowing all along or being a mutant/alien, yadda yadda...)
Third Panel: Charles doesn't believe her.
Fourth Panel: Moira says "Read my mind."
Bottom Panel: Charles scans her thoughts and is shocked she's telling the truth.
Maybe it turns out Krakoa was the true first mutant, a byproduct of the Celestial's tinkering with the planet itself. Or maybe all life on Earth is a product of Krakoa, a "seed of life" terraforming tool used by the Celestials. Who knows.
They gave Krakoa's origin last year, it's just an atomic bomb testing baby.
I don't blind date I make the direct market vibrate
Hickman's X-Stuff looks kinda interesting, I guess, but it's got a long way to go if it wants to be as hype and kino as this new season of Yu-Gi-Oh!
I don't blind date I make the direct market vibrate