City-states have serious vulnerabilities.
In Singapore's case, it depends on gas from Indonesia to run its powerplants.
Most of the food is from overseas.
The world's moving in new directions with the New Silk Road's main artery linking China, Khazakstan and Russia into Europe. Singapore's income from international shipping will further drop as China's goods bypasses the South China Sea and goes overland into Europe in a shorter period of time.
Petroleum refining might be profitable for a few more decades, but coming alternative fuel sources will eventually reduce that sector's contribution to the economy.
Quality of life among the working population is one of the lowest in the 'developed' world, with 'least happy', 'least satisfied' and lowest sex rates in the world.
Singapore has always been a globalist enclave since the British empire founded it as a trading port. It was a place where people came to make money. Those who stayed did it because they believed there was still more money to be made.
Patriotism is for those under mind control.
The here-today-gone-tomorrow immigrants might be from different countries at this time, but the motivations are the same. Once they realize its all a made-up illusion, they will stop coming.
The positioning of the city-state as a place to hold gold and silver will buy it some time. Other than that the only thing attractive is the money and security. Those things are illusionary and temporary.