The differences among the ethnic groups are apparent but slowly changing over time as the groups mix. It seems likely to me that within ten or twenty more generations there will be very few distinct ethnic groups as people intermarry.
This is a good thing, I think, because two or three more generations of white-only marriages for my offspring and you'll be able to read through us.
That's not so, humans are a species Homo Sapiens. Within the species, scientists have always identified three races: Caucasian, Mongoloid, and Negroid. There has been some discussion about Australian aborigines being a separate (fourth) race.
Why will it be a good thing to see the white people become extinct? Was it good to see various Indian tribes in the US dissapear? What about the Polynesians and the original Hawiaans? They have mostly dissapeared or will soon dissapear.