To bear a dismissive attitude towards HK politics, or fail to tread lightly in its politically-active youth, does directly threaten the economy of China. Ask yourself, if HK were as irrelevant as you make it out to be, why is Beijing so eager to let the protests end on a good note?
I think the idea of "politically active youth" blossoming into some great democracy drive is just media drivel for Western countries to hold on to their hegemonic power. Look at Egypt, US sold out their ally in Mubarak, talked big about youth bringing in freedom via facebook and social media. The Muslim Brotherhood is elected, everyone freaks out (US and within Egypt itself), military comes back in, and nothing since.
The anti-establishment parties have declared that they support the rioters and would never cut ties with them. So whoever voted for the anti-establishment parties would be voting for the riots. Whoever argue otherwise is just pitiful that includes the pro-Beijing media. HK has spoken and 60% of the HK voters have declared they support the rioters and the riots.
Its a bloody nose to Carrie Lam and no mistake, but probably as much to do with her woeful handling of the situation and the other deeper seated problems in HK as anything else.
I cannot pretend to know the details of the Pan Democratic movement or how true the implied link between them all and the Protest movement really is.
Happy to be educated on this.
Still the time always comes when a protest movement achieves office and at that point the responsibility for sorting it out becomes theirs. It will be interesting to hear how they all respond if fresh disorder breaks out again.
I think SampanViking has made an important point, people were also unhappy with government's response to rioters. Many of these votes could be "protest votes", they don't necessarily support the protest movement, but were unhappy with the government's inaction. The last US election is a great example of this, non-mainstream candidates won a relatively large number of votes because people did not like Trump or Clinton.
Furthermore, the riot card can only ever be played once. Yes, the supporters of the anti-establishment are tacitly supporting the rioting. However, youth rioting tends to be a psychological game rather than political. Kids grow up. What happened to the hippies and Vietnam war protesters? They became CEOs of today and supporters of Middle East invasions. There will always be some kind of youth movement every decade in any given place (90's anti-globalization, 00's anti-Iraq war, 10's climate change, etc.)
To go further into what SampanViking suggests, what if the anti-establishment carries their momentum and manages to control LegCo? If violence continues, then they are exposed for what they are. If they aren't, then they are tasked with a whole new agenda.
Political reforms are their top priority. Let's say they all agree on this and Central government decides to give it to them. Then what? Likely, the factionization will begin. There will be some pro-independence parties cropping up, there will be others that simply wanted popularly elected LegCo and fade away, Pro-Beijing parties will always be there.
What will challenges would a more "independently" (not independence) minded executive do if they wanted to distance themselves from mainland? First on the agenda would be self-sufficiency, so water and power would need to be localized. As before, desalination plant is expensive and large. Power can be cheap if you build coal, but super polluting, and take away useful land, the terrain is not good for solar and wind, and obviously nuclear is impossible. Beyond that, pursuing self-sufficiency would mean less money for building housing, the biggest issue for most HK citizens. Carrie Lam's Lantau Tomorrow cost 600 billion HKD and was laughed at, what would desalination cost for all of HK, they already pay 20 million HKD per year to GD for water, so the cost for desalination would be far higher and provide no housing. How do you sell this to the population? Another issue, if you decide to throw HKPF under the bus, what happens when they don't try to control the next riot? This certainly has happened in other places before.
In the end, as it was planned, Beijing sits in the catbird seat. I think they held off on any intervention because their planning horizon is so much further ahead than what we are used to in Western countries. The result of this election, it actually shows 1C2S is working. If they allow reforms, they look benevolent. If they continue with 1C2S as it is, then they are still allowing HK autonomy. The only way they can look bad is if they actively intervened (politically or paramilitary) which they did not. The anti-China arguments will dry up over time.