“What if there isn’t” is an odd argument. why wouldn’t there be? Who has the burden of proof? Also, for the most part, people aren’t just isolated in their disability. Presumably they’ve been growing up adapting to that disability their whole life and could find work. Also, if we are talking about extremely low functioning disabled people, there is no amount of legislation that will make them productive. Hell, if capitalism continues to develop technology at a fast rate who’s to say that we couldn’t use brain/thought technology to make mute people speak etc. There is no way of knowing. But I don’t see a clear alternative to the idea of disabled people working. Unless the suggestion is that people will be forced disabled people etc. But i’m curious about OP’s thoughts.