Hypothetically, what would happen if republicans run out of Americans to exclude?
It's hard to answer a question that starts with a false premise
The Lord Humungus.
Notice how even the snake handlers pose as being multi-denominational these days?
Lone Star Patriot
That's not a hypothetical. It actually happened in the early 1960s when LBJ supported the Civil Rights Act. That's why racist southern Dixiecrats abandoned the Democrat party and started voting Republican. Conservatism is a never-ending process of excluding "others" until finally the GOP will consist of a single middle-aged white guy named Earl who sits on his porch polishing a shotgun and muttering racial slurs.