The outcomes of my combined population model match my definition of “worlds” – practically isolated systems that people inhabit: A small population (less than one-hundredth the present number) living off the land and the scraps of our civilization; a population a little larger than ours, limited to the Earth and relying on totally renewable resources; or a much larger interplanetary population, limited to the Solar System and using entirely renewable resources; or a population that grows and then sheds people, by death or emigration, while consuming no more than a maximum amount of renewable resources.
The first world would result from using almost entirely non-renewable resources. It could be realized between 50 to 200 years from now, depending on whether and how fast we acquire new resources.
The second world would be the result of extremely rapid growth of renewable alternatives to energy and production, with us using entirely renewable resources within 60 years. No new non-renewable resources will have been found.
The specifics of the third world depend on how fast we can acquire new resources. For it to exist at all, we would need to have enough non-renewable resources to offset the depletion of non-renewable resources being used to support the population and eventually accounting for all of our consumption (likely within 400 years).
In each of these alternative worlds, people would be limiting themselves to what can be regenerated on an annual basis. The conflict we are currently experiencing between competitors and cooperators will be present in each of these worlds as they deal with the necessity to curb consumption to the renewable resources that are available. In these cases where the speed of travel is limited, there would be no more resources for use in expanding the population and keeping it coherent; we would all need to become cooperators or at least restrain the behavior of competitors.
The fourth world would come into existence if the need of competitors to acquire more resources from themselves could not be controlled. The competitors could then either leave to start other worlds (emigration) or be allowed to kill people. Because the efforts of everyone are necessary to sustain consumption, overall consumption would drop with population, and resources would then be available for growth. The world would cycle between growth and death, growth and emigration, or some combination of both.