Well, I think we've got some folks, right here on this thread, who would argue that a world without strict zoning, and all the legal baggage it brings, would be a world where cats would lay down with dogs, where day would be turned to night, where the fabric of time and space itself would unravel...
But I think that we'd simply have a world where it was a bit harder for people to mind any business save their own.
That's a very good, and sadly unanswerable, question.