Again I agree with some of your thoughts Robert - especially that the most difficult aspect of climate/ecological breakdown for rich countries to handle - politically, socially and ethically - will be the mass migrations out of areas rendered unlivable or infertile. But I think you’re generalising too much again when you see overpopulation as as the key issue (making it in a sense everybody’s fault).
There is no real evidence that the Earth can’t sustain it’s current human population - which most experts project will begin to decline very soon anyway (see Danny Dorling’s book Slowdown).
The fact is, it’s very comforting for the relatively wealthy to frame environmental crisis as having a pretty natural cause like population - and there is often more than a hint not just of casting the blame on humanity as a whole, but on people living in poverty in other countries that have too many children.
But the facts are that the poor in general have little impact, while the rich are responsible for most of the damage. To focus on population is a distraction, when the essence of the problem is not that there are too many people, but that a relatively small number have been tricked into wildly irresponsible and unsustainable consumerism.
There has been a lot of discussion of this in the climate/ecological breakdown thread, eg…