Not sure I agree. As the middle class rises, comfort also rises. As long as the government can provide them with that, protests are unlikely. Those who are not wealthy are typically trapped behind the Great Firewall, completely oblivious to what's going on.
In fact, my extremely wealthy friend here essentially wished death upon the HK people at one point, genuinely emotitonally anngered and upset by their brutish uncivilized behaviour. Does that sound like the narrative of an affluent, empowered individual?
This person is very well educated, with VPN access, but their natural state of media consumption is casual, so they only get the one side: HK kids are evil.
I don't really see any evidence that people are increasing in frustration at the CCP. And those that do simply say they'd rather not talk about it because everything they do is tracked and watched