>China is going to have a massive data set... of Chinese citizens. With how much the ruling party exercises its authority over the nation and the nationalist nature of a lot of Chinese culture I don't see how this data will be broad enough to leverage against other nations in terms of making things like behavioral predictions

You're falsely assuming that these "national" data sets are inaccessible to anyone outside the nation. Hackers, advertising companies, ISPs etc will gladly sell you a copy, which can in turn be duplicated and resold across the world ad infinitum.