Considering that very many countries are at or below
replacement, the general notion isn't automatically wrong.
Replacement is about 2.1 children per woman. The world
is at about 2.4. More than 80 countries are below 2.1.
Nearly always, as technology spreads birth rates fall.
People find other things to do, and they find ways to
not have children while doing them. Condoms, pills,
notions, lotions, etc. and etc.
And abortions. 50 million abortions in the US since
How this will play out in 20 or 30 years is difficult
to be confident.
Just to play with the idea, suppose that there is a
genetic pattern that causes people to continue to
breed under increased tech conditions. And suppose
there is another pattern that discourages breeding
under these conditions. The breed-in-the-face-of-tech
genes would clearly become more common. So in two or
three generations, anybody who still likes lots of
kids will come to dominate the gene pool. Those families
might start to pull the birth rates back up.
But I'm not prepared to take any bets in either direction.