This program is mainly a fig leaf defense that Waymo can trot out when it is criticized by transit proponents. Which is totally fine by me. Train transit as it exists in the US is largely indefensible. We will be better of the sooner we can rip up the tracks and put those right of ways to better use (AV and bike lanes).
I am not sure which rail right-of-ways in the Bay Area could plausibly be justified for AV lane deconversion. Maybe the ailing VTA light rail?
But an "AV lane" will very quickly converge on the traffic characteristics of a regular road.