Those who control the "means of automation" (robot factories, power stations, etc) --let's say 0.01%--, will rule over the rest, in gated communities and closed enclaves.
A small percentage of the population will live alongside them, in B-rated residences, to provide them services that, either still need humans or are better done by humans (e.g. sex), or its considered "classier" to have humans do for you (e.g. cooking). Let's say that's a 10%.
The rest 90% will be left to rot in urban and suburban slums, develop their own black economy, and shot on sight when they dare enter the rich areas.
Which coincidentally was a basic insight behind Karl Marx's communism -- not referring to the regimes it inspired, but to the idea that with the advancements in capitalistic production, distribution will be key to ensure a fair society.
In the end, a powerful 0.1% that can produce anything they want with robots, can use a small number of humans, say 0.9%, for service and such necessary jobs, and will have no use for the rest 99% of humanity -- which could be let to sort it out in slums.
Also the idea behind lots of dystopian fiction -- from Soylent Green to Elysium, and the reality in many places in the third/developing world, where there are more people than jobs needed.
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