I really can't imagine 100% unemployment, because I think there will always be a demand for actual human people in some roles: hairdresser, waiter, singer, prostitute, masseuse, athlete, actor, croupier, etc. Will robots/AI be good enough to do all these jobs? Sure, they might even be now. But as long as some people want to be sung to / served by / entertained by an actual flesh-and-blood human, there will still be e…
Sure and there will always be some demand for horses for various purposes but the total demand for horse labour is way below its peak in 1915. Do you foresee any future technology which might reinvigorate the demand for horses?
But I think the future for humans looks somewhat similar to that of horses today; a small number of us will still be "working", but more because of individual preferences than any kind of need.