The idea that robotics, automation, and so on will make humans into “useless eaters” does not hold water.
Labor will always be the most non-specific factor of production, meaning that humans can learn whatever new skills the economy requires. There will never be a general glut of labor.
In addition, as capital becomes more plentiful, the marginal utility of capital (the value of an extra good) will decline and by that fact raise the marginal utility of labor. This means that the uniquely human skills — ingenuity, creativity, problem-solving — will become increasingly more valuable.
And if somehow, implausibly, machines do replace all human labor, that’ll just abolish scarcity and bring about paradise on earth. I think I’d like that.