Hong Kong is a problem manufactured by Xi. Most Hong Kongers identified as Chinese not more than a few years ago [1]. Come 2050, almost every Hong Konger would have lived under Beijing's rule their whole life. The sensible thing was to wait.
But Xi got impatient. So we got this mess. Hong Kong accelerated the outcome for a die cast when Xi installed himself as leader for life.
[1] https://www.reuters.com/article/us-hongkong-anniversary-idUS...