It still looks like magic when I see cars without drivers here in PHX. We'll have them on the freeway soon enough - potentially a game changer for our city
My bet is you'll be amazed by how little changes. Sure you won't spend any time at gas stations/car dealerships and you'll be able to watch YouTube on your commute, but that's how millions of New Yorkers live and, well, it's fine. That is to say, we could have just built subways/mass transit and gotten all of the benefits.
There is a major downside though, and it's that we'll be doubling down on cars. That means all the mining we have to do for all the components, all the road/vehicle maintenance we have to do, all the waste we have to manage, all the pollution from tires, all the space taken up by roads, garages, parking spaces, all the batteries we have to build/maintain/recycle, all the sprawl and isolation we suffer will increase.
I'm a big fan of public transportation, and I think it's sad that so many cities have underinvested. But it doesn't help your point to pretend that commuting on a bus or subway is the same thing as commuting in an autonomous personal vehicle, and these kinds of false equivalencies only serve to discredit mass transit advocates.