I also not worry too much about this demographic "problem". For one, the technology will solve the problems. Robotics and AI are on the horizon, new industrial revolution is coming. Secondly, while it sound harsh, but China lack of welfare system and good pension plan also meant that the state won't be burdened too much by the pension funding crisis suffered by the many developed countries. Basically you are own your own, if you are old and have no saving. Of course, having said that, I think China should start implementing sustainable welfare and pension system for the future generation. Thirdly, also although this may sound harsh, but with lack of good healthcare system in the past and terrible pollution in the past, I'm sad to say that I'm afraid those old folks may not live very long to enjoy retirement. Sad news for families, but probably a good news from the state's perspective. That's why people need to be kind to their elders, their sacrifice for the sake of future generations are so heavy.

If just having more people can make your country rich, China and India would have long surpassed the US.