Will self-driving cars lead to grade-separated cities?

The usually sensible people at MIT's Senseable City Lab are looking at the future of the traffic light in the world of the self-driving car, and predict that its days are numbered. Instead, they propose a "slot-based intersections that could replace traditional traffic lights, significantly reducing delays, make traffic patterns more efficient, and lower fuel consumption." It's based on the principle that if all the self-driving cars are communication with each other and know they all are, they can plan speeds and courses so that they essentially pass through each other. Upon approaching an intersection, a vehicle automatically contacts a traffic management system to request access. Each self-driving vehicle is then assigned an individualized time or "slot" to enter the intersection.