Then what is there left to work for? Also, I thought the job of a society was to protect it's citizens' negative rights (various freedoms from, freedom from want not being one).

I think this might turn out something like retirement, as people will have to work less: some people make very good use of their extra resources, but many will just sit and watch TV. This is a bit in an inherent bias in the HN crowd, because most of us tend to be more intellectually curious and would likely spend the time learning a new language, etc.