I think this is a very interesting and chilling point, especially if you draw the parallel literally. For quite some time, I was pondering the question:"Who is buying though?". I.e if you automate workers out of labor, who are we selling these AI services to?
I guess if global population drops by 80-90℅ you suddenly get a "sustainable" economy, as everything is repriced the economy of scale needs a much smaller scale.
(Not speculating this is a plan, just a thought that occurred to me when reading about horses example)