What about Star Trek?
One thing that always seemed quirky about the Star Trek universe is how the people of that time, 2300 or more, still have the same cultural divisions we have today. Like for example 3 or 4 hundred years in the future does anyone think there will still be accents? It seems more likely to me that everyone would be speaking in a bland new mix of the way people talk today, but there would be a kind of global uniformity ... or even new accents from groups that isolate such as colonists on out of the way planets.
Would there still be competition or animosity between Americans and Russians such that Ensign Checkov would have to remind everyone about everything that was invented by the Russians?
The people in the Star Trek universe are always listening to or watch songs or media from the "old Earth" and so conversant with its history. Even the Klingons know Shakespeare. That part may well be right since real music seems to have ending somewhere before the year 2000. Surely though there would be some form of popular music in the 2400's wouldn't there be?
I wonder what would science fiction that freed itself from this need to pander to readers into the 20th and 21st century?