I think the tipping point for electric vehicle range would be 1000 miles on one charge.
I disagree. The human body has needs too. Most people want to stop to eat and use a restroom around every 4 hours. If you can charge a car in the time it takes to have a leisurely meal, and then drive for another four hours, it should be fine for cross country driving. The Tesla Model S's largest battery provides just enough energy to propel the vehicle at highway speeds for about 4 hours. Also, the supercharger can charge the battery in about an hour. It's almost like they planned it that way!
I'd like to see Tesla partner with a chain of diners, like Denny's, that's open 24 hours a day.