You make interesting points, but how much of a problem really is a dwindling population? Can you provide some evidence of how in several decades we will be destroyed by this problem?
One small example.
A few years ago, a small town in my state found that its sewer system no longer worked. Engineers determined that the town, which had been losing population, was not sending enough water through the system to make it work anymore.
Also, in the last several years, cities have discovered that if there is not enough water flow through the fresh water systems, bacteria will proliferate in them. So, in areas where there is not sufficient water usage, they have to flush the system out from time to time. When, in driving through a city, you see fire hydrants open for hours at a time, that’s usually what they’re doing.
Detroit, I’m informed, has a problem with underpopulation in places. Abandoned houses become havens for vermin, criminals and the insane, making life unliveable for those who remain in such areas, and accelerating abandonment.
Infrastructure in cities presumes a certain number of people being served. Utilities of all kinds are interconnected. If an area becomes severely underpopulated, the utilities, streets, etc, have to be maintained anyway, thus stretching the resources of fewer and fewer people.
Imagine a metro area in which the population is halved. Property values, of course, would plummet. If there were “free” abandoned houses everywhere, why buy one? Wild animals and human assailants would rule the night.
The population of ancient Rome fell from about one million to about 40,000 in a relatively short time, historically speaking. Infrastructure (aqueducts, drainage systems) fell apart, and disease proliferated among the remaining population. Thieves and assassins ruled parts of the ruins and nearly all the countryside because the more civilized parts of the populace were simply too small to prevent it.
After the Black Death, the countryside in many places was so wild that if highwaymen didn’t kill you, wild animals were likely to do it.
Imagine driving through a largely abandoned countryside. One would not want to have a flat tire after dark. In 1776, the population of the U.S. was spread over a thin slice of coastline. The rest was a howling wilderness. Now, of course, people have spread throughout the country. Again reduce the population significantly, and whole areas would have to be abandoned again, simply because they could not be maintained or policed.