There was a similar story about the ascendancy of Japan over the west in the 1980's, but demographics eventually slowed Japan's growth. There were simply not enough young people to keep the economy growing and take care of the growing elderly population. A similar thing is happening with China as many young people chose to not have children or only have a single child. So far in human history this trend towards fewer children in advanced societies is irreversible. The successful parts of the "west" have counterbalanced this trend by attracting and integrating young immigrants (both educated and working class). Unless China becomes a more attractive place for immigrants it is probably nearing its peak potential.