That's an open question. An autodrive in traffic might be much more practical if it can either predict or communicate with the autodrives in all the other cars, rather than having to adapt to our erratic meat-oriented behavior.
What I'm predicting is a ban on manual control in heavy traffic. Besides any throughput improvement, all-autodrive traffic will probably be safer, which is our priority (to an IMHO unhealthy extreme).
How will an eventual ban (after every vehicle has auto-drive presumably) on manual control have any impact on the initial take-up of auto-drive systems? What you're talking about (if it ever happens) will only happen many years after auto-drive becomes popular.