China’s birth rate is arguably declining because basic needs (housing) and child needs (education and child care) became expensive, applying back pressure on fertility (which is why the CCP and Xi is pushing “common prosperity” hard). People are selective on children already, which I don’t see a problem with; this is a natural result of a free society with healthcare where you can selectively terminate pregnancies you don’t want. During IVF, we were offered the option to sequence the genome of candidate embryos and pick which we wanted based on traits. The future is now.

If this creates cohorts without the ability to partner up, them the breaks of free will and socioeconomic forces. Population ballooned, and it will be painful as it contracts. Humanity ran up the credit card of population growth, and it will have to be paid back (socioeconomically speaking, with unrest and economic contraction) .