I'm hoping the "worst case" you state becomes real, because that would be a great case! Blogged it here:

After "AI": Anticipating a post-LLM science & technology revolution

https://www.evalapply.org/posts/after-ai/index.html

I, for one, welcome the coming age of the post-LLM-datacenter-overinvestment-bust-fueled backyard GPU supercomputer revolution.

(edit: in which case, I'd say more people would get paid to build more of these, except not as obnoxious township-destroying behemoths ... the community library, as opposed to the giant book seller in the cloud)

(edit 2: And I'd go as far as to say that it is anti-employment-generation to allocate economy-scale capital to a very small number of very large scale industrial installations... You wanna incentivize a large number of small-to-medium ones instead, that employ locally in many many more places. That is how you win back industrial capacity.)