Meh, I don't think they'll need to. Somewhere on the Tesla website there is a cute little calculator that will tell you how long it takes to fully charge the Model S with the various charging adapters. As I recall, the 110V / 12A outlet takes something like 4 or 5 days. That's fast enough that most people could probably keep their drive-to-work car at a mid-range SoC by charging all night and while at work. But that doesn't leave any room to really use the car for any errands. I have a feeling that very few owners would consider that a viable option for long-term ownership.