Ok, so if we don't get off the planet in the next n-years, the whole thing collapses or ... we work with already occurring phenomena and ride the population cur

Ok, so if we don't get off the planet in the next n-years, the whole thing collapses or ... we work with already occurring phenomena and ride the population curve down to get to the natural load carrying capacity of the planet WHILE we also become a multi-planet species. Don't let your goal of "fully automated luxury gay space communism" force your risk curve into oblivion.