I strongly recommend anyone following this thread to also watch this video:
https://youtu.be/GSfeZWvCeBY?t=471
As we all know an invasion of Taiwan is bad news as the US would be pressured to support their interests in the region. I wouldn't be surprised however if North Korea doesn't take advantage of such a situation. If that is the case then there is no reason why China couldn't also take advantage of the situation and invade Hong Kong to assert their dominance over their claims over HK.
The US then seeing this as a greater threat also support Hong Kong. Russia then seeing this as a threat to their interests sends troops to Hong Kong Taiwan and the Chinese border.
I doubt Japan would be given up easily.
The only thing preventing this would be the Covid-19 lockdown easing and all western economies globally recovering and relations with China improving over time. Hopefully Trump doesn't win again.
I don't see the Chinese man-made islands being of any threat to anyone, an artificial Tsunami from a water detonated nuke could probably wipe them off the map quite easily.