What if in an Alternate Timeline, the Vikings migrated to Americas in much larger numbers and settled there, eventually mixing with Native Americans, along with mixing Culturally, Linguistically, etc by the time the Columbus and other European Seafarers reach the Americas?
You could have different empires across North America, with more Viking ones with little Native mixture, towards the Northwest America and Sparsely populated regions and more and more Native, towards the Southeast, becoming full almost majority to fully Native American, after to the East of Central USA, wherever there were large Native Populations.
Let's say they are mostly immune to the Old World diseases by this time.
So how do you think this would end up?