Comment by diffxx

The instantaneous fertility rate dipping below replacement level does not mean humanity dying out. It might mean that this particular civilization with this particular population level is. Infinite growth ad infinitum leads to an inevitable (and likely catastrophic) collapse. No one can say with certainty what the "correct" fertility rate is. That being said, if a society is set up as a pyramid scheme, it must have infinite growth to sustain itself so I won't argue that this way of life is likely dying.