The thing with China though, is that it consistently has something fall apart right before it makes the transition from contender to influencer on the world stage.

Historically it has been famine, but other times it has been the cultural emphasis on being the best copier of ideas (the civil service exam used to be about who could recite the teachings of Confucius the most actually, not who could create the best new interpretation), and not on creating original ideas. When you're at the top you must create original content.

And the third case, although not relevant this time, is the lack of maritime tradition / cultural emphasis on exploration. So somewhat related to point two in that there's little drive to explore the unknown.