Warmaking is not as profitable as it used to be. And its only decreasing. What has China to gain from invaded HK ? Problem solvers will just move to another region. If its aggressors vs problem solvers, later does not need former at all. To defend PS dont need gun, embargo will work just fine.
They don't post anymore.
Instead, the fierce and low-margin/high-risk compitition actually exist between aggressors 1. for the control of same region (eg Saudi Arabia) and, 2. providing same product (eg crude oil).
Handling "the barrel of a gun" does not mean you have to fire it. China just made a combination of statements (notably the fact that the New Territories reprensenting 75% of HK's land were on a lease expiring in 1997, that they would not negociate on) and threats that resulted in the UK handing over HK on a platter. At that time (1997) HK by itself represented 15% of all of China's GDP, so Beijing definitely gained quite a lot by acting tough, even if they never had to pull the trigger.
You may not fire it but there is cost of creating and maintaing a gun. Yes there might be skirmishes during birth of City-as-a-Service industry. But it will stablize as military states fails to find enough revenue to sustain itself while also maintaing welfare spending.