You have limited time; I'll keep it short:
Have you noticed you're now not the only one (mostly) living in a single person household, not in your social life, but without significant other?
The single person household has been the fastest increasing type over the last few decades. In many countries (Japan, Germany, Russia) they are not even reaching replacement level, with enough new births to keep the population stable. (These are by far the leaders in the world, not the followers.) China achieves the same result, of the single child family and the generation of the 'little emperors,' by decree.
Two can live as cheaply as one was always a dubious proposition, especially when likely to become three.
Does that mean the disappearance of the nuclear family? Not at all, but the strains on them are more severe; they can not control the demands made on them, which will increase over time. In cases where the resources remain stagnant, where the offspring fail to provide new resources, they may collapse.
A mystical shift to less reproduction? I think so. (Why mystical? We know all about the mechanics of reproduction, and we know nothing else.)
More mobile, in better fighting trim, richer, better equipped, well networked.
Increasingly clearly those able to give help, not those in need of help.
Just a thought.