How the World Trade Organization could open up Internet access in China
reason.com
reason.com
I feel that if anyone were to pressure China in this manner, by citing this economic argument, it'd be quickly rebuffed by the Chinese as a necessary "political" control that can be found in a number of WTO member states.
Examples include limiting or even prosecuting hate speech (anti-religious, Holocaust denial, advocating genocide), blocking websites with illegal content (drug use, bomb manufacture, child pornography), and so on... The websites most noticeably blocked in China allow user-generated comments and videos that cannot be controlled by the Chinese government, but will have similarly illegal-in-China content (Tibet/Taiwan independence advocates, anti-government protesters).
There's little to this argument without appearing hypocritical to the Chinese government, and the firewall (GFW) is too important to their goal of a "Harmonious Society" - it will fall only if the Party falls.