The best predictor for future behavior is past behavior: China is testing the waters, in some cases in a quite literal sense (South China Sea), and you're correct that how the world reacts to Hong Kong and the Xinjiang "re-education camps" will be seen as a vital piece of information in the future when deciding on how to proceed with other "problematic" regions: for example Taiwan, which in the case where strong-arming the island into obedience, most probably would require military intervention. Before you claim that this is unlikely or extreme, remember that thanks to the PRC, almost no countries in the world even recognize Taiwan as a country -- so how are you supposed to question the "invasion"?
These actions can all be traced back to China's increased tendency towards authoritarianism, for example the elimination of the term limit for Xi Jinping in 2018,[1] which stands in contrast to China's economic liberalization in the early 1990s.[2] It's important to understand that this liberalization is more or less the sole reason China is the "young superpower" we see today (just look up the GDP numbers from 1990 onwards), so the question is how a reversal of this attitude will serve future Chinese interests. Although unconfirmed, there are claims that Xi's grip on power may be decreasing somewhat, and that there is "widespread opposition" from within the party, but for obvious reasons few are willing to speak out.[3]
[1]: https://www.nytimes.com/2018/02/25/world/asia/china-xi-jinpi...
[2]: https://en.wikipedia.org/wiki/Chinese_economic_reform
[3]: https://www.theguardian.com/world/2020/aug/18/china-xi-jinpi...