What he's saying is incentives in these countries are just not aligned to creation of families and rearing of children. And it's true, when you expect women to go to school til they're 25, a home requires two incomes and then some, everything is taxed to the breaking point, and birth control is ubiquitously available, you can expect a decline in fertility to the point that you eventually have a demographic crisis.
Our countries resolve this by importing people from countries with more people than they can handle, but if you look at the situation globally, as countries become richer this appears to happen universally. It's a matter of 100 years until we can't play this population shuffling game anymore and we will experience a global fertility and demographic crisis. And what's more, it appears that it is unavoidable and it's not clear if humanity will stabilize to a population level or if these fluctuations are inevitable. See https://fractalfoundation.org/OFC/OFC-6-1.html
Our countries resolve this by importing people from countries with more people than they can handle, but if you look at the situation globally, as countries become richer this appears to happen universally. It's a matter of 100 years until we can't play this population shuffling game anymore and we will experience a global fertility and demographic crisis. And what's more, it appears that it is unavoidable and it's not clear if humanity will stabilize to a population level or if these fluctuations are inevitable. See https://fractalfoundation.org/OFC/OFC-6-1.html