What if the Ghost Dance worked?

I'm sure this sounds stupid, but hear me out.

The Ghost Dance was a Native American spiritual movement in the late 19th Century when a Paiute prophet named Wovoka claimed to have had a dream (exact details vary) where God showed him a vision of the Natives being taken up into heaven and the Earth swallowing up all white men in North America, after which the Natives were returned to the Earth to live happily. Wovoka claimed that if enough Indians danced in a certain way, this would become a reality. The Ghost Dance movement swept across the Great Plains and the Southwest, but the US reacted with fear and hostility, and the movement largely died out after the Massacre at Wounded Knee.

But if it worked, what kind of society would the Natives build, once they're in what is essentially a post-apocalypse? What would the Mexicans do (assuming they're still around)? Would the British try to reclaim Canada and go even further south? I think it's a pretty interesting one to think about at least, because the overnight disappearance of America and Canada would leave a massive power vacuum right in the middle of the world's second wave of colonialism.