Given the rate of exponential advancements in science and technology... self-repairing hulls should probably have been invented before the NX-01 was launched.
Given the kind of technologies we have in development already, you could have a liquid like alloy to come into place of a hull breach and then solidify once its in place and of course, because the hull would (obviously) be made of programmable metamaterials, it would shape itself into what's needed (windows indents, etc.).
They should have been using nanobots for starship construction by then realistically.
We already have a molecular synthesizer technology which was demonstrated in 2015 and again in 2018.
Nanobots were made in a lab and we are expected to have them in wide-scale use by 2030 when they are cheap enough to mass produce (of course, if money was not a limiting factor, most of these technologies would already be in use right now... a ridiculous type of technology could have been used back in 1974 that would put most of what's used today to shame, but we did not due to 'cost efficiency' - otherwise, we had the resources, the know how and technology to implement that in sustainable abundance - and given how Starfleet and the Federation at large don't use money, 'cost efficiency' is not a factor... they'd be focusing on 'technical efficiency' with 'sustainability' in mind).
Most of Trek writers didn't (and couldn't) necessarily predict where real world technology would be today.
Mind you, some had good visions, but unfortunately, a lot of information did not proliferate very fast in the 1960-ies (even though a lot of what was invented back then was already quite amazing, and not accessible to everyone given that you couldn't just pull the information up on a computer screen).
Setting everything so far into the future seems a bit unrealistic (not to mention that Warp drive is way too slow in comparison to where it should be).
Self-repairing hulls should be a standard by the NX-01 launch, along with even shields (as we ARE experimenting with this technology already).
Looking at the time frame between TOS and TMP for instance, I think they've given it a good overhaul by leaving the time lapse the same as for the real world.
That said, TNG should have similarly taken place 15 years after TOS (and probably featured a Galaxy class ship called something else - can still have the same crew though).
You could easily still have same design changes, etc. in such a time span... given how fast things change in the real world, they'd change even faster in Trek.
Setting Kirk and TNG about 70 years apart was a mistake. Too much time has elapsed with too little changing (apart from say the Federation growing) - that just doesn't make sense.
A society like the one we saw in Trek would not be susceptible to stagnation.
Warp drive should have been much faster in the 23rd century, allowing the Federation to travel from one end of the galaxy to the next in say a 150 days (150 000 ly's - equating to 1000 Ly's per day).
With the Excelsior Transwarp for example, that could have been increased by a factor of 10 (10 000 Ly's a day - or basically Warp 9.975).
By the mid 24th century, they should be having exploratory missions to other galaxies (along with outlying bases there) - that's what 'realistic' portrayal of exponential advancement might look like.
Voyager could have been thrown 273,750,000 L'ys away and still the writers could have said it would have taken them 75 years to get back to the Milky Way by using Warp 9.975 (because, that's what I calculated exponential Warp scale would look like past Warp 9.9 and canonical statement that its 21 473 times LS) - that's how powerful Warp engines should be by the late 23rd century.
24th century could have had outlying colonies and ships exploring other galaxies.
With 10 000 Ly's per day, it would take a ship 270 days to reach Andromeda for instance.
Oh and Biological immortality should have been a long time standard by NX-01 era.
We will have it in the real world by 2030... or possibly accessible for everyone by 2039 (if we retain Capitalism and massive inequality we still have).
So many things would need revamping to make Trek more 'in line' with reality (and no, it wouldn't be 'too advanced').
It would still take large amount of time to explore the entirety of the Milky Way even with superfast ships and very powerful sensors.
Milky way too much? Set the story outside the galaxy... in the intergalactic void.
Man, Voyager might have been even better if it needed 75 years to cross 273 million Ly's... the show could take a more science based turn to explore what's happening in the void between galaxies, while (mostly) meeting new species in a galaxy they encounter.
