American libertarian activist Patri Friedman thinks that the future of the city-state are 'seasteads':
Patri is taking the Silicon Valley mindset and applying it to the nation-state. There are all these things you could now do that didn’t exist when our current system of government was invented, he told me. Constant online direct-democracy voting, building smart-cities, using crypto-currencies. And yet we still use a 19th-century model. (Source)
An alternative to the floating city maybe reclaiming reefs, such as that which is happening in the South China Sea
The question that such ideas pose is:
What if Silicon Valley’s core beliefs — even the benign ones — are wrong?(Source)