1) In theory, the top predators, humans, can live in a mix of economically defined communities which we see, in a small part with some religiously defined communities that interface with the more developed. How simple may never be fully defined based on level of technology and other benefits which can be accepted. And therein lies the question.
2) While the consumptive economy can accept an amount of shift in resource demands ( lower use and increase in use with new knowledge), those at the bottom of the economic level have no upward boundaries.
3) Across the spectrum from excessive consumption to severely restricted access, there is still the sense that planetary resources are limited. Thus the issue is still distribution. A levelized population in both bio/physical resource use and, more importantly socio/economic access and privilege without a benevolent dictator can not be envision much less realized in practice