China has gone from being the 4th largest economy to the second largest in only 24 months.  The Chinese navy's first aircraft carrier has begun its sea trials; its common knowledge that these carriers are designed to widen a nations millitary reach http://www.bbc.co.uk/news/world-asia-pacific-14470882 The question is when not if China occupies the number one spot with a matching millitary might, how will they act towards the world?  Will democracy promoted by the west become a thing of the past? Will Mandarin become the dominant business language? Will,

In my opinion, China will only overtake the United States in terms of becoming the world's largest economy. (That is likely to happen within the next 15-20 years). Militarily, China is still decades behind the US. Don't forget that the Chinese economy is still being sustained mainly by US consumption.

Being a world leader goes beyond having the largest economy, such a country should also be able to export its culture to other parts of the world and gain widespread acceptance. No other country has been as successful as the US in this regard.

In summary, China's limiting factors include (but are not limited to): An extremely difficult language to learn, poor human rights record, deep suspicion and mistrust by other countries due to their approach to business, a government that is increasingly intolerant of dissent, contribution to global warming and apparent lack of respect for religion. For these and other reasons, I believe that the US, in conjunction with the EU, will retain cultural and technological leadership in world affairs, even when China becomes the world's largest economy.