I think what you're trying to say is something like "people won't work anymore but they will be able to stay home and take care of their elders". Which I think is a valid point, but also one that is only true for a really small minority of the population, certainly not enough to justify putting the whole population on welfare.

Consider this scenario: you're taking care of you elders and you need to go out and buy some medicine. But the drugstores have all closed, since nobody wants to work there anymore (why would they? They're at home taking care of their elders too). Do you think this is not a realistic scenario in the long run? Why not?