Human population growth has slowed, even gone below the replacement rate in several rich nations. China's one-child policy has suppressed population growth but created an imbalance within the population age groupings and, due to unchecked grotesque infanticide of girls, more young men than women. India and central Africa population surges. Migration to richer nations will increase the working populations and the net consumption of resources within the capitalist world. There is no escaping the Overshoot Gap.
I regard the population of high-consuming middle-class in emerging economies of concern. The shameful refusal of the USA to recognize its disproportionate damage to ecosystems and depletion of resources creates a major obstacle to an essential geopolitical treaty to contain GHG. The absence of an international consensus on global warming explains much of my pessimism on the Climate Catastrophe that surely awaits the World.
Nobel economist Paul Krugman provides a useful overview of low fertility in the USA. The proportion of retired seniors to productive younger workers can cause fiscal shortfalls, already huge and mounting, and generational friction. Full disclosure: I retired in 2015, supported by savings and retirement funds to which my wife and I have contributed. My wife and I have never been unemployed since the age of 16.
The easing of population pressure provides some room for closing the Overshoot Gap. The increase in consumption, however, creates a challenge. Automobiles could be Electrical Vehicles and electricity could be renewable, but the stress on the load to the planet will still rise, perhaps by not as much.