OK the inter-vehicle communication and crowd sourcing and AI sound like they will manage it. I'm assuming though that we'll eventually want AV-aware sensors attached to every light and every stop sign and every intersection. UHF RFID or some such that is cheap to deploy.
I think there'd be massive cost in retro-fitting lights and intersections - probably easier to agree on a mechanism for new infrastructure, and rely upon current approaches for extant infrastructure.
My concern is more about the regulatory side -- before any of this stuff gets widely deployed, various authorities are going to have to come up with some standards, and for the most part nation states are spectacularly poor at doing this sensibly in isolation, and horrendously woeful at doing it in cooperation. I suspect we'll end up with cars & infrastructure that are not 100% interoperable across borders.
