It will be interesting to see what the US resembles when its numbers exceed 1 billion people. China in many ways is simply setting the precedent now, how the US follows remains to be seen.
The U.S., like Canada, Australia, Brazil, and many Spanish-speaking countries in America, along with the former colonizing countries of Western Europe (e.g. England, Holland, France), is an immigration-based country, and so birth rate is only one factor. Given the number of people from China, India, and elsewhere who would immigrate to the U.S. if they could, it's not inconceivable that one day the U.S. will welcome them and their money so Americans can profit from another residential property Ponzi scheme.
Though note that it really is long-term.. it takes a couple generations for the population to stop increasing after birth rates drop, since the previous generation still contained more children.
It'd be great if these optimistic projections are what happens, but today's american culture and economy is still very growth centric - I don't see it happening.
