That's not a tax to the mainland, but new operation cost per national security commitments. Though technicalities aside, it could totally be exploited as a new tax that could be as onerous as politburo decides. HK autonomy is definitely over, though I surmise it's future is still indeterminate. There's good case to cultivate the city for another 1C2S model closer to Singapore, but it will take time, and indoctrination via patriotic education of new youth cohorts to produce a society that's more compatible with CCP 20 years from now. It's the last peaceful 1C2S gambit within reunification time frame.

I don't know how the article about PAP relates, though I was going to mention in the original comment that HK wouldn't take more few PAP detachments to tame even without "military" intervention. The key point, being that it's not a "frontier" territory and surrounded by so much CCP para/military/security that secession is not possible.