1. Reproduction is already heavily subsidized in many countries, be it direct grants, tax breats and so on. This is nothing new.

2. Most people actually want children. Getting someone to actually procreate with that will share burden.

3. Investing in children should hel to fund future pension payments. There is pretty good case for self-interest.

4. China won't care, neither will Russia or other parts of world.

5. Countries that will do that will have a better outcome than countries full of retirees. Unless AI takes over, natural selection will take care of rest

If this happens, I assume Chinese breeding facilities will optimize for producing children with high cognitive ability. Via selective breeding, embryo selection, or genetic engineering.