I'm posting as a Chinese (second-language) speaker here who grew up speaking English and who has endeavored to maintain a bilingual home in the United States. Amazingly, only just more than half the population of China itself is conversant in Modern Standard Chinese.

http://news.xinhuanet.com/english/2007-03/07/content_5812838...

So Chinese still has to gain a lot of use at home before it can gain major use abroad.

Several of the other comments about the importance of network effects in favoring one language rather than another show what a tremendous head start English has as the interlanguage for varied ethnic groups all over the world.