China could pose a problem eventually.
Short term. Tiawan vs PRC could become a real to life issue, and depending on the world's stance (mainly the US) things could get ugly, and quickly. Though, this isn't likely (for the moment) as Taiwan businesses have over $40 billion invested in China, and China recognizes that while they would love to destroy Taiwan it would be in their best interest to turn it into a special administrative region, like Hong Kong or, due to its strong independent economy, a special economic zone like Shenzhen, Zhuhai, Shantou, Xiamen, or Hainan Province. Taiwan
Long Term. The PRC's going to have some interesting dilemmas on its hands if it continues to seek economic liberalization while clinging to political control. The two are hardly complimentary. At the moment, China doesn't really have any other option than to focus on itself, fortify its economy and shop around quietly for future endeavors. One certainly cannot mistake the current lack of a capability for a long term disinterest in expansionism. The concept of a Greater East Asia Co-Prosperity Sphere is alive and well, a few hundred miles to the West of its former home.
What I do think we will see very soon, is that they'll become our major competitor for consumer markets, resources and political and military influence.