It's probably of our own making and not something foreigners do care about - but the problem today is how to make people comfortable at life enough to at least have 2 children, something that is the basis of a functionning society (meaning it can renew itself).
You can have less children if you want, but us I think we need this as a goal: we already do pretty much less than 1 per woman, so we already achieved your dream.
We all will struggle in a long, slow decline, given that the earth will be able to maintain fewer and fewer people in the century to come due catastrophes like global warming.
The "China cannot get weak because that leads to others prospering and we wouldn't want that" thinking is deeply flawed.