Although the content of the article is interesting, I don't like how the author is basically concluding: Because the one-child policy is introducing dynamics that are different from the past, it's dangerous.
Most things are not any different from those currently experienced by western countries: declining fertility rate, aging population, etc. The only thing that's really in the unfamiliar territory is the male:female ratio imbalance.
What would really have been unprecedented was if the one-child policy was not implemented and population kept growing unabated. I personally think there would be alot of social problems had this been the case.