[0] https://en.wikipedia.org/wiki/Ford_Model_T#Mass_production
Not really, given that the article goes into detail about this in the first paragraph, with US data and graphs: "Then, between 1930 and 1950, 90% of the horses in the US disappeared."
The point isn't to claim that motor vehicles did not replace horses, they obviously did, but that the replacement was less "sudden" than claimed.
I just googled "average horse lifespan", and the answer that came back was, exactly, "25-30 years". There's a clue in that number for you.
The working life of a horse may be shorter than the realistic lifespan. Searching for "horse depreciation" gives 7 years for a horse under age 12, the prime years for a horse being between 7 and 12 yrs old, depending on what it is used for.
I'm willing to accept the input of someone more knowledgeable about working horses, though!
I agree with all the limitations you've written about the current state of AI and LLMs. But the fact is that the tech behind AI and LLMs never really gets worse. I also agree that just scaling and more compute will probably be a dead end, but that doesn't mean that I don't think that progress will still happen even when/if those barriers are broadly realized.
Unless you really believe human brains have some sort of "secret special sauce" (and, FWIW, I think it's possible - the ability of consciousness/sentience to arise from "dumb matter" is something that I don't think scientists have adequately explained or even really theorized), the steady progress of AI should, eventually, surpass human capabilities, and when it does, it will happen "all at once".