Native American resistance what if's come up fairly regularly on the board, and, as I often respond, I don't think there is any real chance for North American Natives to effectively resist European encroachment past maybe the mid 18th century.
That said, an interesting, if rather depressing, POD idea came to me the other day: how plausible would it be to have an "Easter Rising" on one or more of the largest Native American reservations at the point when US military forces are at their highest commitment level overseas in World War I, and the mainland US government is also distracted dealing with the influenza pandemic? Where would the weapons come from? How many Natives could participate in the uprising? And how long could they hold off US national guard or military units before the inevitable conclusion? What long-term effects would the memory of such an uprising have in Native American consciousness? Considering the Irish Easter Rising spurred major changes further on, despite it being as thoroughly and bloodily crushed as would be a Native Rising in TTL, we could see a very different 20th century for Native Americans, but what exactly, I'm not sure. Thoughts?