I think it would be a huge effort to set all of the roads up like that, and, with time, manually driven cars will most likely become less common and perhaps disappear completely. When that happens, it would be a huge effort to change the roads again. I feel like the best way forward is to integrate them gradually, and as new roads are built or old ones are overhauled, maybe include features that accommodate driverless cars better.
The world health organization claims that approximately 1.24 million road traffic related deaths occur every year, with between 20 to 50 million more people suffering non-fatal injuries!!! A lot of these are people in poorer countries, so self driving cars won't fix everything overnight, but self driving cars aren't susceptible to intoxication, fatigue, emotions (road rage etc.), speeding, distractions, texting while driving etc. They should theoretically be able to see and monitor the position of every car/bike/pedestrian in their 360 degree field of view at all times. They should be able to perform much more complex calculations than humans too! And, when all cars on the road are self driving cars, they should be able to communicate with each other which will further increase safety. The fact that self driving cars can and will be safer is pretty much indisputable.