Thoughts on Ethnicity and Identity in Far Future Sci-fi?

My general rule is that if you don't have anything worth saying about identity subjects, there's no reason to highlight them in your work. Whether that's race, sex, gender, sexuality, nationality, etc... Obviously, you can't avoid grounding contemporary or historical fiction in extant cultures. In those cases (if I'm not centering an aspect of identity to make a point) I just try to be respectful, informed, and consciously inconspicuous with representation.

But when talking about centuries or even millennia into the future, I find the existence of current day ethnicities and other identity norms among humans a bit... backwards? Having white, black, asian, latin, etc continue to exist as distinct ethnicities and cultures in the far future has dark implications about ongoing segregation in that setting's history. Not just physical features, but names, languages, dialects, aesthetics, etc...

Of course in live action you have to cast real people, who bring the features they have from the real world. But in writing, animation, or games; in the world building itself, how do you handle this subject in your writing and why?

I have my own thoughts, trying to balance representation, verisimilitude, and aspiration with the story's themes. But I'm curious to hear others'.