What if we accept the other side of the curve, instead of fighting it?
So many assumptions about limitless market growth, about the underlying reasons to want a higher birthrate at world population scale. Per economy? Sure there are issues. Massive issues. But, the French (and Russian) approach of bribing women to have more babies may not be the best path out.
Many social services & benefits are designed under an assumption of growth. Ofc we can change the assumptions but this also requires changing the programs, either making them less generous or raising taxes. Neither of those are vote getters, so politicians & govt staff feel a strong incentivize to try anything but those. We can try to make it up with immigration too, but at the scale required, immigration is also unpopular.
I don't think there's any silver bullet here.
Merkel and Immigration to Germany comes to mind.