When this happens, costs for virtually everything will more or less go to zero, because we can make humans to make more humans to make everything else in our society that costs money. Try to imagine a society where virtually everything is free...visualize walking around and getting free coffee from Starbucks, free rides from Uber, free meals three times a day, free healthcare, free housing, etc. If everything is free, there isn't really a need for work and income at all. We're much further off from what you are suggesting than I think many proponents of AI realize, but this would be the other side of that coin.