I don't see how this will fly even with robot taxis. Not for too long at least. I think self driving cars will be commoditized easily. Any new player can simply leverage the technology. The economy of scale is simply not there in this business, compared to the leverage Google and Facebook have. There is hardly any network effect, and it is still highly capital intensive even with robot cars. So while they may succeed in being and maintaining their status as multi-billion dollar companies, I am not seeing how they can go much further in the long run.
Completely disagree regarding the network effect of Uber vs. Lyft. The system is highly network dependent. Most Uber drivers would prefer to drive for Lyft because Lyft pays more (partially why they're losing more money than Uber), but in most markets Lyft doesn't have as many riders that use the service. As a driver, you want to maximize time spent with a fare vs. fare-hunting. Similarly, as a rider, you are weighing price vs. time meaning most people will pay more $ to wait less for their ride.
Most drivers I talk to drive for both and keep both on, but get more pings on Uber than on Lyft. In SF Lyft has more mind-share and it's a more even split.
FWIW I've lived in both SF and NYC since the rise of these services.
But that type of network effect is easily undermined by a service that offers cheaper fares. I saw this happen first-hand in India where Ola cabs, which was being used by almost everyone, quickly started losing users to Uber once Uber started their massive discounts and promotion series in India.
Yeah, as in people will be able to mod their existing cars to be self-driving and then rent them out AirBnB-style when they aren't using them. There's even a distributed storage system already built to handle that ... people's driveways and garages.