What happens when every single physical and mental job that could be done by humans is done by AI/robots? Sure, you'll always have people imagining and creating

What happens when every single physical and mental job that could be done by humans is done by AI/robots? Sure, you'll always have people imagining and creating new things, but it doesn't seem wise to tie that to economic compensation when technology reaches a state where every single human being gets to experience an upper-middle class American lifestyle, unconditionally, from birth to death.