Well, my question implies that being a landlord would be a remaining source of income, for starters. But if that landlord also owns the automated farms and factories producing consumer goods without labor, then the people they're renting to really might not have any other income. At any rate, where a UBI is substituting for employment income that someone used to earn, but is no longer able to, then I don't think the renter gains purchasing power to pay more for rent. (They do gain free time though).