It would seem no organized movement has come forward.

Yet. Enough people haven’t felt the weight of the looming disaster. Too many still think their relative privilege will spare them, because when has it failed them before?

I believe it will happen, but whether it happens in our lifetimes remains to be seen, and whether it happens on purpose is unknown. At least part of that will be decided by the groundwork we lay today, and the more the existing institutions fail people, the more likely they can be persuaded to a better cause.

No global powers oppose the eating of the Earth.

They caused it, and they benefit from it. Why would they oppose it? Even if they think something should be done, they are more blinded by their extreme privilege than the rest of us.

Like you say, I think humans will go back to smaller tribes and local government, though I hope we can lay the groundwork for them to be less warring and insular and instead, more cooperative.