I think most people discount the effect that connected cars will have on safety even when you have mixed levels of human operated and level 1-5 AVs. If a car operated by a human has even a basic connected control system in it then a AV can simply communicate that the driver is about to hit the AV and the human operated car will take some basic corrective action.

The interesting tech is not only AV but the infrastructure where cars communicate automatically about which lanes there in, what their intentions are etc.

The current use case I think is cool is a car comes up to a slow truck and the truck communicates to the car that the passing lane is clear.