Race, ie differences in physical characters between humans in different regions, only came about because groups were separated by geographic barriers, only bred with people in that area and thus developed regional characteristics.
But already in the modern world all the geographical barriers have come down. Interracial breeding is extremely common which means a mixing of racial characteristics. "Race" will gradually disappear as the defining traits are blended away.
There will still be some people born with lighter skin or darker skin, but they wont identify with a particular "race" only the culture they are born into. The colour of your skin, slanting eyes, etc wont mean anything about who you are, what culture or nation you come from, anymore than brown eyes do today.
It is also possible (in fact likely) that genetic engineering will mean you can choose particular features you want your baby to have. (I'm gonna make mine have pink hair and x-ray vision).
Some races have already disappeared, for example the Ainu of Japan. They werent killed off, they just interbred with Japanese until no distinction between the physical characters of the groups remained.
However, new races may emerge if, for example, groups of humans are isolated on other planets, or in generational spaceships. But the characteristic that develop will probably be different from the ones that developed here on Earth.
P.S. Did anyone notice that in the show, Dec 31 2999 is a Tuesday and that it really will be a Tuesday? Impressive!
Joseph Abbott
"I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world, because they'd never expect it." - Deep Thoughts __