Earlier quoted context omitted.
IMO calling it "population collapse" and a "train wreck" is the wrong way to describe it. This isn't so much a collapse, it's a leveling-off. A train isn't supposed to wreck, but populations are supposed to reach a maxima. The fact historical short-sightedness meant we didn't plan for it properly is an issue. The problem here should be framed around our economic system though, not fertility rates.
We aren’t really reaching a maxima. There are no constraints preventing population from growing other than people not wanting to have kids. That’s not a normal constraint. That’s … kind of bizarre.
I've come to believe this is what reaching carrying capacity is supposed to feel like. A gradual desire to have fewer kids due to stress, rather than an abrupt calamity that cuts of populations all of a sudden.