10 is optimistic IMHO. The popular 80/20 rule is at work here. It's going to take a lot of time to get the rest 20% right. For example, how long it's going to take to solve the driving on the snowy roads?
I, for one, have never taken a Lyft from San Francisco to Tahoe.
"On the roads" doesn't mean "Every single road in every single market around the globe"
5 is maybe doable in a limited context, e.g. in residential neighborhoods of American cities. No way for the rest of the world though. The road systems are too complicated.
Seems like that's plenty enough to be a large and growing business, though?
Snow.
Not even. We are at least 5-10 years away from operational fully autonomous cars being used in production in the bay area. There's really no timeline at all for when we might have an operational autonomous car that can handle driving conditions more severe than light rain.