I have a bet with a friend that in 6 years there’ll be autonomous-only highway lanes somewhere, like HOV lanes we have today. It makes perfect sense to me. If you have part of the road where you can predict how every vehicle will act, especially if they can coordinate, you could end up with basically a high speed train of tightly packed vehicles zipping along at record traffic densities.
It's been my belief for over 20 years now that dedicated/instrumented roads for autonomous vehicles is the only way autonomous cars will ever be a thing, at mass scale, other than via the invention of true AGI (which I still don't think we're close to). Such roads becoming a thing within the next 6 years though, I'd doubt.
I think there might be a trial stretch of road somewhere in a few years, although surely not widespread. Such a thing feels inevitable to me, though, if we’re going to have self-driving cars at all.