Well, perhaps... I can't help but suspect that extant socioeconomic factors are contributing in ineluctable ways to the current decline. Various pressures, like delayed reproduction (extended education and age of consent increasing), economic forces (rising housing and other costs), and population density induced social neuropathology (like lemmings, people get nutty when packed like sardines), all are both strongly exerting negative reproductive influence on affluent populations, and quite temporal, as well as unpredictable.

Feminism, Antifa, and corrupt gummint would make me less prone to passionate breeding.

Hell, Imma become a monk, now.

Edit: I wonder if affluence induced reproductive repression has acted throughout history to weaken empires, making them more vulnerable to barbarian hordes? 0_o