The article is interesting throughout, here is one good bit:
The foremost difficulty is immigration. In English we'd call it "migration," but our translators unfailingly used the word "immigration," and I began to see that it was the more accurate description of what was happening. Just as developed countries like the United States and members of the European Union face an influx of workers from the developing world, so does China: it's just that China contains both the developed and developing worlds within its borders.
The way China regulates this flow is not that different from the way nation states do. There is a residence permit called a hukou that anchors people to their home region by tying social services (healthcare, pension and, most important, schooling) to that area. But just as walls and laws have a hard time restricting human traffic from Mexico to the United States when the economic incentives are so extreme, so do the internal regulations of the Chinese state.
Pick any major city in America and start adding 500,000 people a year. It wouldn't be long before it broke under the strain.