Humans overall
Posthumans
Sentinels/Nimrod
Xeno-type groups
Orchi
Other mutants
Alien civilizations
Something else
Who has enough power to do that, though? For all the talk Magneto and Apocalypse and the like have been doing humans are so lowly and beneath them; how would they even get close enough to destroy the island? What would?...or are we assuming they'll keep the same lax security measures as in X-Force? I mean yeah, that wouldn't be totally surprising but...I gotta be honest, I'm gonna have to start callin' 'em morons if they do...?
And, no, either way; that doesn't justify hatred against all humans in such a murderous fashion. One does not speak for all on what someone might do. And even so, if anything that'd Moira's fault for banning pre-cogs.
Or the reaction once other mutants are aware of that rule. That may bring some division.
Mystique is already about to wreak havok in X-Men #6.
How will the kids react to Charles refusing to bring back Blindfold?
How will Legion react, if their relationship is still cannon? Is he alive? Is he even allowed on Krakoa? One of his personnalities may have precog too.
Bringing back the old, killing the young: that's the Marvel way
After a couple of years of circling the unique concepts that Hickman came up with, with no real progression, the biggest threat would be reader apathy.
Well I'm not saying hatred against humans in a murderous fashion, but what if that law leads to their downfall? What if Bill the Merc is let go and he returns with an army of posthuman Sentinel Nimrods, or the data he gathers is used to destroy the protocols? What if "rufus" is actually a Nimrod he's building?
The question isn't whether the law is right or wrong, it's what if that becomes their biggest threat.
"Danielle... I intend to do something rash and violent." - Betsy Braddock
Krakoa, Arakko, and Otherworld forever!
I guess I'd have to see the reasoning behind it on Bill's part. Even then, for all the preparation mutants have been doing against those threats I'd be really friggin' interested to see what exactly takes them by surprise there.
Then again, it would really be irony; Magneto's been talking about how superior he is and how humans are so evil...hm.
Ya know, I'm not saying I support that, but if it did happen to take Magneto out first...
Revolution? But it is not necessarily a bad thing, rather a natural evolution. As long as they are under pressure and threats, mutants of Krakoa are unite and rather tamed.
Maybe, after a while, they would want a 'regime change'… democracy, elections, unions…
“Strength is the lot of but a few privileged men; but austere perseverance, harsh and continuous, may be employed by the smallest of us and rarely fails of its purpose, for its silent power grows irresistibly greater with time.” Goethe