The reference to Diamond Age was more a allusion to delusions of the elite rather than a prediction of any sort. If I were to predict, I'd be thinking more Snow Crash, or else, par preference, All Tomorrow's Parties.

Meanwhile, if the rich can't build diamandoid islands, they can buy Paraguay. Or London. Or Dubai, more likely, which is a fabulous example of what these people in fact have in (what we may as well call a) mind. A totally artificial slave state built on foundations of sand and artfully situated by the rising tide.