The biggest question is missing from the proposed research list at the end

"What will the chat bots that offer frictionless relationships do to birth rates?"

> You can try to consolidate people into fewer towns and smaller areas, but human mobility is not infinite; some people will be stuck in decaying towns, rotting away in despair.

This is a red herring. Look at Spain and Italy, where dead towns litter the countryside. Some people still live there because they want to, and not because they have to. Relocation efforts of even moderate means capture the 99.5% who are willing to move to where infrastructure still exists.

And where I stand, the fertility issue - aside from environmental factors like microplastics that introduce endocrine disruptors - comes down to systemic economic barriers.

In the past, families gravitated to having lots of children because they could start helping around the farm or working in the factories from a very young age. And in this manner they directly contributed to the revenue of the family as a whole, allowing the family to grow to many children. This was a fact until the early 20th century. Plus, the lack of fertility controls and lack of reproductive agency and autonomy on the part of women generally led to large families by default.

Then we had the fertility revolution, where women were not only given tools to control their fertility, but were also given fuller participatory agency in the economy instead of being totally financially dependent on her husband. Naturally, many to most women aren’t interested in becoming brood mares - almost all women tend to prefer somewhere between no children and four children, with an average that is around the replacement level. That alone wouldn’t have caused our current “crisis”.

But now we have entered into a viciously dangerous stage of end-stage capitalism, where the Parasite Class have become insanely greedy, desperate to Hoover up wealth from every possible source. This driving down of wages and cranking up of costs means that dual-income households have moved from an option to an absolute necessity, to the point where healthy dual incomes are barely able to support both adults, much less any children. And because offspring are now unable to generate profit for families for a good two decades (until they themselves become adults), couples have therefore made the painful decision to limit children to one or even none.

TL;DR: our current “fertility crisis” comes entirely down to the greed of the Parasite Class, who have put the working class into a vice that squeezes them from both ends, and makes having any number of children a very financially irresponsible choice.