This almost feels like the Blu Ray and HD DVD war - yeah, Blu Ray beat HD DVD, but digital beat out both. At what point do self driving cars mean that Uber no longer has a competitive advantage in transportation? Aka if you remove the need to sign up drivers, then you're just competing on cost of a vehicle + overhead as the cost to a customer to switch from Uber to say 'FordNow!' is so low - I just download another app.
Uber is competing with all forms of transportation and to beat everyone there is a long time to try to wait and stay solvent for.