If they are building-up to acquire resources, then folks in eastern Russia and Southeast Asia should start getting nervous. The PRC wants the ROC for political/nationalist reasons. As for resources, the PRC has long had it eye on the rest of the continent of Asia and the western Pacific.
Why Southeast Asia? With the exception of Vietnam, most of the countries there are on very friendly terms with China. Chinese practically own most of Thailand already.
Paul - you had a map that showed the Evil Empire after the conquests. It would fit right in here.