We're at a point right now where the cost of gasoline has the potential to make a lot of people look for an alternative in their next vehicle. That might be a natural gas powered car, it might be electric. Or it might be a service.
I think people avoid the math on cars. If your entire family could go everywhere they want in a month, with no auto insurance bill, no gasoline bill, and no car payments or repairs. How much would you pay for that? If a car service could provide that for $500/month would that make you consider moving? How about $200/month? What if gas hits $7/gallon?
People love their cars. But cars are a recent invention. And while they love them being their personal space, people are also cheap. However this plays out it'll be interesting.