still it could take years. Why not wait out the rioters for several more months? Then the HK government can reassess the situation and make adjustment accordingly. 

And there is one key difference: in 1989, the protest was in Beijing, the seat of  the government. There was the real danger of it spreading to other groups and areas. Today, it is HK...nearly 2,000 km away and while it is an important city it is NOT a vital city to China and accounts for only 3% of GDP. Most importantly: the majority of the Chinese citizens are not supporting the rioters.

The other thing is that it only took me 10 minutes to figure out two very viable strategies to neutralize and nullify any action by the police to enforce the law. How long will it take the rioters to figure it out?