The birth rates and aging population in China are a big concern for the Chinese people. They are definitely considering changing the one-child policy. They’ve also realised that the one-child policy creates kids that are spoiled rotten, called the 4-2-1 syndrome (4 grandparents, 2 parents, and one kid). There is a growing number of people in China who are having two and three kids, regardless of the consequences (all financial BTW), because they too have the same belief as you.
My point is that a lot of Chinese who want to have children will find themselves unable to do so because of reduced fertility due to pollution and a poisoned food supply. And that is starting to bite right now. It happened in Russia too.
Yes, this is one area where I am wishing the Chinese people will push the limits of the law to have mulitple children. China made alot of wise decisions in regards to their economy, but this method of social engineering will only bring poverty in the long term. China is projected to only have 1.45 billion people by 2050. But if China steers her economy correctly and people pursue the right priorities, I don't see why China couldn't be a developed nation by then and still have a population of 1.7/1.8 billion people.