Doesn't solve the worst part of parking: reserving that much space for car storage.
The author's vision seems to be one in which everyone owns a self-driving car. Why own the car? Just pay for use, Uber et al. can handle logistics. Only the reserve portion of the fleet should be parked, like buses.
In the city, I couldn't possibly agree with this more. When I lived in Boston I sold my car after the first two years because it was a ridiculous expense and hassle for the utility. Taking a cab a few times a week turned out to be cheaper than parking tickets alone.
Given a choice though, I much prefer to live in less densely populated areas (e.g., northwest Montana), and owning a vehicle is really unavoidable. In these places that also means a 4x4 SUV or truck, not a Prius, or else you'd be calling a tow truck every 5 minutes in the winter.
I would expect driverless taxis to end up like public toilets.