He was too far ahead of his time. Let’s say you have a floating fission nuclear reactor that can put out all kinds of heat. You then dredge ocean bottom mud from 2 miles down to the surface. After drying it out you make hemungous amounts of bubble-filled buoyant glass. You then make floating islands with it.
On about 5% of the oceans surface you could have enough space for a city-block sized island(a family of 4 on 330’x330’)for every one of 7 billion people, a “maui” for everyone. Why go running off to mars as an escapist/survivalist when you could have your own maui in pleasant tropical climes? What would YOUR island design look like?
In THE FLOATING ISLAND, Jules Verne describes such an enterprise. His idea was to bolt together large boxes of plate iron. In the story, an island of several square miles is constructed this way, and a conventional town is built on it.
Verne had unlimited faith in riveted plate iron. The Nautilus goes to the bottom of the sea on the strength of this construction.