The point is that we seem to be stuck in the 1970’s thinking about the “population bomb” popularized by Paul Ehrlich. The bomb was a dud. Fertility rates are declining, a trend which if continued will lead to an inevitable demographic winter.
This trend is, in my view, far more threatening to world societies than most things currently being talked about including environmentalism and global warming. If there are no people, we won’t have to worry about either of those.
There are all sorts of incentives that governments could take to help increase fertility rates. The tax code should favor marriage and there should be substantial increases in the dependent exemption. Society ought to encourage earlier, not later, marriage.