In fact, the Betancores are an excellent example of good far-future SF writing that features different races. Too much SF assumes that, in a few thousand years, Africans will be Africans and Chinese will be Chinese and Americans will be Americans and so on and so forth... But the Betancores are dark-skinned, but clearly not Africans. They have Greek names and their own culture, unlike any Earth culture. They are Glavians. Even authors I adore, like Cordwainer Smith, have a bad habit of exporting current stereotypes into the future, mostly around Germans, with his Sixth Reich/Menschenjager, and Chinese, with the conquest of Venus and Lord Loveaduck - and don't start me on Star Trek, and their planet of Irishmen. Bleh.