Looks like this is where we're heading at least for the Model 3 (and possible future Models S/X customers who have not already been promised "Free for the life of the car" by Tesla) and I think it's a really good thing.
Tesla Model 3 'Supercharger Credits' discovered on 'MyTesla' page
It would be nice to see the details on how this will work, but I agree that long term something like this needs to be done.