"Despite being unenforceable outside Hong Kong, it is applied across the planet"
Ah, so they have the USA approach to law. Good for them.
In any case, I note that "The exodus from Hong Kong to Singapore is well underway ", which is perfectly normal.
Yes, Hong Kong will become just another Chinese city. Yes, the Great Internet Firewall will be thoroughly applied. Yes, anyone with any sense of freedom and a smidgen of intelligence should get the hell out of there while they can.
There might still be money to make in Hong Kong, but it will be under Beijing's full control. Your choice.