Self-driving vehicles could be at your door within a 1 minute timeframe (say). That's a huge change, and will nullify the benefits of owning a car.
Of course, this will be possible because driverless taxi companies will have the logistics in place to make this happen (they know where every car is, and they can compute where to send empty cars to increase the capacity).
I can imagine that a cheaper service will offer the same but, say, in 5 minutes.
Also, you will never have to find a parking spot, which may be an even better argument.
