I know we're all guessing here, because I assume you don't work at Andreessen Horowitz, but I don't agree with the bet you're making. When it comes to online services, China has a tendency to adopt their own versions of services started elsewhere. For example, Google is dying hard in China [1]. The players in the social media scene are similarly unfamiliar to users outside of China, with Weibo leading (I'm lacking citation here).

If Github sees China as an opportunity, they'd better move quick, and look very deeply at what has allowed services like Baidu and Weibo to trounce American-born competitors in their market.

http://www.techinasia.com/china-baidu-qihoo-google-search-ma...