My firm belief is that we will have to design roads for self-driving cars before self-driving cars will be the majority. Right now roads are approximately desi

My firm belief is that we will have to design roads for self-driving cars before self-driving cars will be the majority. Right now roads are approximately designed for human sensors. We need roads designed for machine sensors. If we started today, and during every repaving we built roads for machine sensors, we'd have the roadways where most miles are driven repaved in about a decade. I don't know exactly what it will look like. It might looks like RFIDs embedded in roads, it might looks like self driving car lanes (similar to carpool lanes of today), etc. Until this process begins of redesigning roads for machine sensors, I'm not really optimistic for self-driving cars. I think you're right about the 20+ mark.