Although I admit I have a slight repulsion to the thought of a few billionaires being able to wield almost complete autonomy, and assuredly the tech billionaires have a vested interest to build these cities such that the inhabitants depend on their technology (e.g. what would happen if Google built a city, and look how convenient it is that the ISP is Google Fiber, with Google self-driving cars servicing the roads, etc.).
In any case, I wish any effort to re-think how we build towns and cities the best of luck, because it feels like to me we've been grasping this (failing) strategy of car-addiction for far too long now, and it's draining our society financially, environmentally, and socially.