I'd say that's up the the indigenous folks. I don't have a very detailed opinion on it in large part because no one will ever ask me for help drafting the landback policy, but in general terms it's a safe bet that indigenous peoples engaged in a struggle for liberation will typically approach the issue of other peoples' liberation humanely.

The few indigenous voices I've heard talk at length about landback have been opposed to creating an ethnostate, even in cases where the leadership is meant to be fully indigenous. It's worth noting that ethnostates as we know them are contingent on global structures of white supremacism to shape racial dynamics

Actually, have you listened to Blowback? Season 2 covers the Cuban revolution and that's probably a pretty good primer on this sort of thing. Cuba didn't automatically exile anybody en masse, they left on their own accord because heaven forbid they had to live with the locals on equal footing. The rich Gusanos leave on their own. In the case of the US, they would probably become refugees over in Western Europe.

As I understand it, Native Americans would be given sovereign control over their territories and us colonizers would become citizens of those territories under their governance. It'd seem unlikely they'd want to automatically exile everyone en masse from those territories... unless we've given them a reason to...😅

All whites get sent to the blender and we get blended

If it does happen, it'll be within an occupied North America, after its defeat in WW3.

By force, likely.