@hightor,
It's a hell of a good question.
I'm surprised that China hasn't yet gone heavy-handed/murderous. But that they haven't suggests they don't see this as anything like an easy solution.
All the video we're seeing of the conflict shows how many individuals are filming all these incidents with their phones and digital devices. That's a clear difference from the Tiananmen case and certainly makes China's potential moves much more complex. It seems pretty certain that the protesters are counting on this to constrain Chinese actions.
There was some press coverage I read earlier suggesting that the younger (student) component is now being supported by middle-aged professionals. I gather that is a consequence of Hong Kong's traditions of independence and, of course, Chinese promises to maintain/permit a relatively high level of independence. If that's accurate, this doesn't make China's attempts to run the place as they'd like any easier.
My personal response to the more extreme acts of defiance (fire-bombs, property destruction) has been, "you dummies!". Such acts seem to me to play right into China's propaganda needs in a way that non-violence doesn't. One would actually expect Chinese agitprop agents to do this while pretending to be part of the protest. But mostly, these are young people with the typical perception that they are invincible.
I don't know how this turns out but it is encouraging that the protesters haven't been crushed under the treads of tanks yet.