>Not thinking so much small, voluntary communes but at the sort of scale of a modern city or State.

Funnily enough, I remember going to some talks about something called "Economy of Communion", to which an audience member asked a similar question.

The response: think globally, act locally. I wish I could remember more about the explanation, and although I remember not being completely satisfied with the answer, I also remember thinking that it made sense and it's probably better than the alternatives.