Yes, settlers tend toward fascism as things heat up. But there's the potential for indigenous movements to grow in response to fascist oppression, as more people who previously were numbed by the gains of imperialism are marginalized. I single out indigenous movements because they have always gotten a completely raw deal and settler states have, by definition, no business cutting them a piece of the pie; that contradiction affords some space for the rest of the marginalized people to coalesce.

The entire historical process doesn't happen in one fell swoop, there are stages and plenty of time for enough people to form a resistance which is absolutely invaluable for the anti-imperialist projects in the periphery to exploit. I'll always remember that when the Weather Underground visited the Viet Minh, the request the Viet Minh had of them was to build a mass movement instead of focusing on grandiose acts of adventurism. The fact that the only hope for avoiding certain doom lies outside of the imperial core doesn't mean we have nothing to do but wait for the bombs to land.