If we just take it as a given that we should allow autonomous cars to self-coordinate traffic intersections (a big if), this proposal still makes no sense. The traffic light is actively yielding control to the autonomous cars. In that case, just let the autonomous cars set the traffic signal appropriately.
You don’t need a “warning” light to tell drivers that autonomous cars are in charge. You need to set the traffic light to the right states. If you can’t do that safely, 100% you’re saying that you can’t let autonomous cars control the flow of traffic through the intersection.
This whole “just follow the car in front of you” directive is a poor attempt to handwave away human drivers. “Look, if we can just make the humans drive as if they are autonomous, there won’t be any issues at all.” It’s absurd and shipping a system like this would be criminally negligent. “Just follow the car in front of you” is not just a lazy answer. It’s nonsense guidance when you need to make a left and the autonomous car in front of you is going straight. “Oops. We forgot drivers sometimes need to turn.”