Would it be 80s technology everywhere but widely deployed? Or would things have advanced further - better compilers, more ergonomic languages, better platforms etc? I don't know. But I suspect we'd still have needed people studying computer science to advance the state of the art.
Now looking forward 30-40 years from now, will everything still run on 2020s technologies?
If anything it seems wide deployment of LLMs would go against this. When nobody writes code by hand anymore, who will care about the ergonomics of programming languages? And even if a few do care, how would you get adoption? I expect everyone will just use whatever is already used most.
It seems that now more than ever, testing is important. But LLMs love to cheat the tests and make them superficially pass. If you're never reading the code, how do you know changes are reasonable?
Do you see lots of posts about new compilers and languages and language features on HN in the last year? Maybe I just missed them. I'd love to read more posts like that and fewer about agent frameworks.