I think you might be a bit off here on the extent to which the average driver will be needing gasoline.

Tesla's have less than 10% battery degradation after 8 years so far.

What will happen is people will buy an electric car as a second car. They'll get comfortable charging every night and then buy a Chevy volt like car that usually won't need gas but can range extender as needed. A large portion of those users will realize you don't even need the range extender most of the time.