Not just that, they’ll specialize completely: there will be warrior planets/races, and agricultural planets/races, and science planets/races. There will be no explanation of how the warrior races managed to evolve and colonize the galaxy without anyone procuring food or building the spaceships.
It’s nice to see that a lot of others think along the same lines regarding futuristic clothing. Apparently knits are going to be very popular.
There will be no country/western music anymore…
And Roy Orbison will still be wildly popular.
The best fighting gear for women will be the chainmail bikini.
As will San Francisco’s Golden Gate bridge.
Female experts whose professional expertise and reputation suggests at least two decades worth of study and experience , will still have a listed age of 27. They won’t have glasses, either.
You merely have to be “destined for greatness” or some such, to be allowed to leap frog your promotions over all of your vastly more experienced and accomplished peers.
Heck, we can pretty much fix that now. Just a matter of cost. 
Not that it matters from the bad guys’ POV, because they can never seem to hit anything anway.
Earth is destined to become the capital seat of power for a vast, galaxy-spanning federation of planets (or sometimes empire), and Earth humans will become a dominant life form in the universe, despite the presence of vastly superior (both physically and technologically) races like Vulcans, Time Lords, or Daxxamites. Also, the fact that Earth is in a relatively backwater corner of the Milky Way galaxy won’t hinder it from being a major major hub of intergalactic trade and politics.
Cybernetic enhancements will always, always, ALWAYS lead down a road to a dehumanizing transformation into robotic monsters. Whether it be Robocops, the Borg or the Cybermen - using bionic replacements (even in cases where limbs were amputed or lost in accidents) will result in the loss of a persons’ (or species’) soul and basic humanity.
Everyone will dress in full-body S&M leather fetish outfits.
The profit motif will be gone by the 24th Century, except for outsiders like the Ferengi.
People will instead focus on being the best they can be. The best Admiral, the best Starship Captain, the best garbage scow Captain, the best new recruit aboard a Starship. Or aboard a garbage scow.
Nobody, but nobody, will care about Latinum, etc.
Except, for some reason, Tom Paris, before being recruited to help Tuvok round up the outlaws.
Of course, you can’t actually use the galaxy’s actual hub as a hub, it’s probably a giant black hole.
Yes, just like now. 
What?
:o
I really need to broaden my circle of acquaintances . . .
We should hang out.
This is because shirt collars evolved to enormous proportions until they collapsed under their own gravity to completely disappear.
Which is to say all cataclysmic natural or extra-terrestrial disasters will only strike major metropolitan areas, iconic cities and landmarks of note.
All planets and moons explored upon by mankind have Earth-gravity somehow.
All post-apocalyptic Earth environments are endless, arid, scorched deserts in which paper has become a material of awe, myth or legend.
All alien planet deserts, invariably, have some sort of giant sand worm.
Interior living spaces will be either immaculately clean, scrubbed to the surface molecules, or spectacularly squalid.
Most spaceships are made up of an enormous amount of bashed together model battleship and fighter jet parts.
Neckties will be gone because the traditional collar, as we know it, will be gone. Men’s collars will be of the mock turtle neck or Nehru type. No one will sneeze. Ever. No one will burp, pee, shit, or fart either. The words shit, piss, fuck, cunt, cocksucker, motherfucker, and tits will still be taboo. No one will wear a wristwatch.
Dune and Hyperion say hi… I mean salaam
All cloth, such as blankets and clothes and even table napkins, will be shiny and metallic and/or covered in glitter.
The most fashionable clothing styles will include rings circling the body, hovering with no visible means of attachment.