If the price of consumer goods and basic necessities of all types fell to almost zero, but we had large-scale technological unemployment (most people don't have a job and thus have little money),
You are assuming that most people wouldn't have a job. I think most people would have jobs if scarcity only ended for consumer goods. We would still need plumbers, teachers, lawyers, cops, firemen, soldiers, doctors, investors, scientists, etc. The scary part is when AIs can do those jobs as well.
I'm not assuming that most people wouldn't have a job, at least not at first. I think that if unemployment goes above about 15% or so and stays there, the whole system starts to become unstable; that's the point where you tend to get either political change or revolution, if people aren't able to fill their basic needs.
Most of the things you list are actually professions that are mostly hired by the government itself, and the govenrment shouldn't have any shortage of money, since it can still tax the lights-out factories that are producing everything. ...
Kevin Drum has an article in Mother Jones about AI and Moore's Law:
Although he only mentions consumer goods, Drum presumably means that scarcity will end for services and consumer goods. If scarcity only ended for consumer goods, people would still have to work (most jobs are currently in the services economy).
Drum explains that our linear-thinking brains don't intuitively grasp exponential systems like Moore's law.
He also includes this nice animated .gif which illustrates the principle very clearly.
Drum continues by talking about possible economic ramifications.
Drum says the share of (US) national income going to workers was stable until about a decade ago. I think the graph he links to shows the worker's share has been declining since approximately the late 1960s/early 1970s. This is about the time US immigration levels started increasing (which raises returns to capital and lowers native worker wages).
The rest of Drum's piece isn't terribly interesting, but it is good to see mainstream pundits talking about these topics.