This is not the first time the HKPF has used overt force on a protester, just the first time it has done so publicly. Several protesters have already been "disappeared", and there are many stories coming out of brutal torture against activists. If Beijing authorities have learned one thing from Tiananmen Square, it's that in the internet age violent suppression must happen in private places, where it cannot be recorded by someone's cellphone and shared instantly with the world. Public acts of violence is a PR nightmare and only fans the flames of dissent.

This event will only harden HKers more. In the short term it might prevent mainstream protesters from taking to the streets out of fear of violence. But it will make the average HKer more resentful of Beijing's long arm and empower radical factions. And there are many ways to weaken a government's control outside of public protest.

EDIT: Protester is in critical condition. He was not killed.