I agree completely that the angst in HK is caused by outsiders. It has to feel terrible for HK people having their representation grabbed by agents of Beijing. They should apologize and grant universal suffrage to all people born in HK.
Most important in this is HK establishing its own military service, intel service, constitution (not just the Basic law oath of fealty to PRC), and UN representation. These are the remaining things HK needs to be treated like any other nation.
Since the rule of law is what matters, it will be important that judges and lawyers have adequate time to adapt to the any changes in the legal process after transition is complete.
The thing that has yet to be decided is how the legislature in HK will be structured though. Maybe in /r/hongkong they can bring it up.
But most important will be China staying out of meddling in Hong Kong's internal affairs. This is about Hong Kong people planning new system separate from PRC. After that is complete PRC has the same right to establish treaties the same way as Japan, USA, etc.