Autonomous cars probably make transit optimization easier, but there's a tradeoff here that doesn't have very much to do with autonomy: The more people in the car, the less convenient for each rider, both because of comfort and delaying the trip with stops. It's basically the difference between a cab and a shared ride van today. It's certainly conceivable that cabs mostly disappear and are replaced by shared ride vans, but lots of things are conceivable...

Autonomous vehicles will be electric but so will some (perhaps a smaller fraction of) non-autonomous vehicles. Anyway, that doesn't save the calculation. It's clear all these benefits are there but maybe not to the degree you claim, at least not in such a simple way.