Also, consider that tesla essentially owns the largest amount of electric stops in the US. They've got their foot in the door, no other manufacturer is going to come close. When electric cars really kick into gear, tesla controls the gas pumps, and can charge everyone else, while still giving free to their own cars, which is a pretty good incentive.
(it's never been "free", just added on to the purchase price as an option, and later as a standard feature)
Ignore the editorialized headline. The actual quote is:
>The obvious thing to do is decouple the Supercharger Network from the cost of the Model 3. So it will still be very cheap—and far cheaper than gasoline—to drive long-distance with the Model 3, but it will not be free long distance for life unless you’ve purchased that package. -- Elon Musk http://www.plugincars.com/model-3-owners-will-pay-access-tes...
Tesla has the technical capability though to sell Supercharger access in time-limited slots (unlimited Supercharger access for the next 7 days, good for that coast-to-coast trip one is planning), on per-kWh basis (plug in, have your credit card on file with Tesla app, start charging), as well as introduce variable pricing (more expensive kWh during periods of heavy use and long lines at Superchargers, cheaper and/or free access during periods of low activity). Historically they've been very driver-friendly, so if I had to guess, they might make all of those options available, as they each cover a specific use case.