First, clickbait headline much? The actual statements by the PRC seem much more reserved, as par the course. Though I guess different people have different standards for "outrage."
That said, I don't think Mattis' statement means much in the long run. The US has been affirming its commitment to Taiwan even after it recognized the PRC, and it will do so even as it also affirms its commitment to the One China Policy. (Remember when Trump's major scandal when he called President Tsai and questioned the OCP? That turned out to be a whole bunch of nothing as he too reaffirmed it.)
Anyways, the PRC will remain hellbent on reclaiming Taiwan and when there's a will, there's a way. Given the increasing disparity between the two, said reclamation is inevitable. Let's all hope that it's a peaceful one, where the PRC respects Taiwan's unique features a la Hong Kong and Macau.
Taiwan is not not going back, and any situation where they end up like Hong Kong would be a complete betrayal by the free world.
Why not? The Chinese people and the CCP both desperately want to reclaim Taiwan in order to reunite the Han people. To them, Taiwan being
de facto independent is a reminder of the times when China was weak and powerless. China may be strong today, but without Taiwan the Chinese civilization cannot be complete. Thus reclaiming Taiwan is at the core of Chinese national identity, as much as the ideals of democracy and freedom are to Americans.
More "practically," reclaiming Taiwan would remove any possibility of a Cuban Missile Crisis situation off the coast of Fujian.
Meanwhile I highly doubt the United States would have a comparable appetite to protect Taiwan. The shadows of Iraq and Afghanistan are long and dark, and that was with two minor powers, not the second most powerful country in the world. Even if an American president wants to intervene, they would be limited in options due to the intensity of China's commitment on this issue (i.e. war
will break out if things get bad enough).
