The average person now is far wealthier in terms of actual purchasing power than the average person 100 years ago, and that's largely because of automation making everything cheaper.
access to housing is incredibly expensive. Measuring their purchasing power for how many scented candles they can buy is pretty meaningless when they are much closer to homelessness than ever before.
It's called Baumol's cost disease.
The people who are "automated away" and have reduced income are also less of a consumer. In a society where most jobs are automated, who are the consumers?
So you tell me: where are the consumers? Why aren't we all unemployed and unable to afford to buy anything now that those agriculture jobs have been automated away? Or did we find other productive activities to spend our time on?
I put the onus on the yay-sayers, can you name a job that a human can do that this new AI / robot cannot (or will not soon) do? Otherwise, I think its time to stop drawing false equivalence with agriculture, luddites, etc. Those were "narrow" machines, incapable of coding, writing a symphony, or working in a factory. In the next decade we're talking about building a better human.
I think a better example is to draw a parallel to horses. There is nothing left for them to do; we keep a few around for sport and entertainment, as a novelty. At one time, they were indispensible, but there's no rule that any organism (including humans) has infinite economically viable uses. At some point, everything worth doing (economically) might be automated to the point that human labor no longer makes sense (and hence we have high unemployment). There is no cosmic law written that "if jobs are replaced by tech, new jobs shall fill the space!" Just look at areas in the rust belt where literally nothing replaced the lost jobs -- there is just rampant unemployment, black market dealing / drugs, and despair.
But yes, if we develop artificial superinteligence to the level where humans become literally useless (e.g. we don't just automate 90% of everything, but 100%, and there's actually no tasks left in the world that humans can do better or cheaper than computers) then assuming humanity survives we'll need a different economic system for distributing the nearly-unlimited resources resulting from that. Probably in that situation the best thing to do would be to ask the AI to design our new economic system, since it would obviously do a better job at that than any human.
Where displaced workers will go though is not something that can or should be planned out in a centralized fashion, because the best answer to that question is different for each individual and depends on their skills, preferences, and life situation, balanced against the needs and desires of other consumers in the unimaginably complex web that is the global economy.
Despite not knowing exactly where everyone will end up though, I think I can still be confident that they will find something, because the incentives to do so are very strong, both on a personal level (needing to find work) and the entrepreneurial level (finding useful things for displaced workers to do could make you very rich).
As another commenter put it a while back, unemployed workers are an unused resource, and the economy is very good at finding uses for unused resources.