I think that if China forcefully suppresses HK, that will drive Vietnam, Taiwan, Philippines, Malaysia, Brunei--and to a lesser extent Japan, South Korea, Singapore, Indonesia, Thailand, Laos, Cambodia, Myanmar, and Australia--into a regional alliance with the US, a sort of ASEAN++/SEATO2. Its major agenda would likely be diplomatically evicting China from territorial claims in the South China Sea, particularly with respect to the "nine dash line".
If HK can be portrayed as the model of what PRC does to dominate, suppress, and assimilate lesser economic powers, and its occupation of Paracels and Spratlys as an overture to securing absolute control over all economic resources in the South China Sea, the neighboring nations will likely line up behind the US to discourage a hot military war, and then do everything they can to close ranks diplomatically and economically to keep PRC from taking pieces of their pie.
The mass-internment of Uighurs is also likely to spur the Muslim populations of Indonesia and Malaysia to wrongfoot China diplomatically and raise international support for sanctions.
China's main crime is carrying a really big stick, and speaking loudly instead of softly. If a country uses its strength too much, then it starts creating problems that only greater shows of force can fix. All that work on soft power in South America and Africa could go straight down the drain.