What do think should be done? Is it Hong Kong just an arena for the two nations battling for world dominance? if so, China might have to forgo Hong Kong! And Hong Kong is unsafable!
By forgo, I assume you mean to forgo fostering it into a valuable Chinese city and turn it into a battlefield of political casualties. Well, in the short term, the only way to save it (other than summoning the PLA to institute martial law) would be to, as I said before, storm it with millions of violent, aggressive young Chinese patriots in red shirts. All law will be suspended due to the overwhelming chaos and it will basically be like the Purge movie series except without guns. Anyone who doesn't kowtow and kiss the Chinese flag immediately gets his/her brains splattered all over the sidewalk with a steel bat. Let the patriots kill the cockroaches and serve them street justice so that by the end, the only ones left surviving can win Oscars for their acting. And soon, they will believe their own act. No pan-democratic politicians who didn't flee in time should be left alive and of course with the collapse of the government, the CCP will take control ahead of schedule. This is a cultural revolution crash course to save Hong Kong very quickly. To the world, the explanation will be simple: no troops were used; the rioters wanted violent democracy to take over, so the Chinese youths gave it to them. They were both out-numbered and out-violenced, thus, they were out-lived. This is the method that I prefer to solve the Hong Kong problem.
But, there are other more tactful ways, which include more waiting and more starving of Hong Kong's economy, and I think even more long-term goals to be considered behind the scenes like using Hong Kong as a portal to damage and drain the Western economies that support the riots. Whether that happens now, soon, in 2047 with the full control advantage, I do not know. That kind of tact is out of my hands and up to ZhongNanHai.
But one thing is for sure; no matter the temporary pain, China is fully committed to saving Hong Kong and making her a truly prosperous city, both in material and finally in spirit.