Actually lots of people are now talking about the problem of too few babies especially in Europe. Many countries are looking to their populations halving by 2100. A recent report says there are 79 countries with fertility rates (mean=1.59) below the replacement level rate (mean=2.08).
There are some negative consequences or at least difficult questions to wrestle with. Where is the tax coming from in a massively aged world? Who pays for healthcare for the elderly and who looks after them? Will retirement remain an option in those countries and will those folk get a pension? Others can comment on the positive aspects of declining fertility.
[ The means are my calculations on dataset in https://www.pop.org/simple/countries-with-below-replacement-... ]
There are some negative consequences or at least difficult questions to wrestle with. Where is the tax coming from in a massively aged world? Who pays for healthcare for the elderly and who looks after them? Will retirement remain an option in those countries and will those folk get a pension? Others can comment on the positive aspects of declining fertility.