IMHO, by the time Xi’s reign is over, he will have made a play for Taiwan. And maybe more. What he’s doing over Hong Kong suggests he’s a man in a hurry. There is no pressing need to do anything about Hong Kong. In fact, it serves the same function that it did when China had a closed economy - it’s an economic valve for China to do business with the West much the way the West does business with other members of the club. By destroying Hong Kong’s protected status, and therefore the economic privileges HK retains with the West, he has signaled that he believes China doesn’t need this outlet.
Is China in a position to complete the task Xi has set out for it? It’s certainly possible. When Japan carried out the Pearl Harbor attacks, its economy (including its overseas possessions) was 1/5 the size of the US economy. China’s economy is half the size of the American economy today.
Note that Chinese conquerors have generally been content with incremental gains, whereas Japan wanted the whole enchilada, with troops positioned a hop and a skip away from Australia. So the entire Chinese military will be focused on its particular region of interest - the airspace and waters around Taiwan, which will make it much more challenging just in terms of the number of Chinese air and naval units that any country coming to Taiwan’s aid will have to face. I also expect him to attempt to cement China’s hold on the South China Sea by seizing foreign vessels passing through the region. We’ll see.
Trying to limit a war to just the aims you want taken is a fool’s errand.
The first casualty of battle is your assessment of the enemies’ reaction.
The adversaries of China could/would move on vulnerable targets outside the Chinese war planners focus (Taiwan).