Demographers were kinda right, it's just that we've had new socioeconomic problems [0][1] post-pill, and we're really starting to feel the effects since around 2008. Post-pill fertility rates in Europe and NA had been slowly rising before that. I think we're likely to fix at least one of these problems in the coming decades. Or rather, we have to because we'd be royally screwed otherwise. And in the event we fail, most democratic societies would turn authoritarian, in which case they'd be able to implement population engineering measures like banning birth control.

[0] https://wtfhappenedin1971.com

[1] https://news.ycombinator.com/item?id=45725009

Due note, I'm citing these sources because they show the problem, not because their conclusions are sound.