500 years into the future the entire world will basically look Brazilian (Afro-European-Arab-Asian)
The only countries I can imagine that would remain ethnostates are China Japan and North Korea because of their rigid ethnic unity and culture.
If a Native American guy marries a white woman and they have kids who are more white who subsequently also marry other people mixed with white does that mean that in the future NO ONE will look like their native ancestors? At what point is someone white