On the one hand, humans are absolute dogshit at predicting the future. I mean, the year 2100? Give me a fucking break. On the other hand, the demographic shift is as convincing and well-supported as any theory in all of social science.

I imagine advances in fertility technology will change the landscape of procreation in ways we cannot yet predict. It's also possible that major catastrophes could change population dynamics, not necessarily by mass deaths, but by driving some populations back along the demographic transition where having many children is once again the best strategy.