That seems like it's a good point, I suspect that we will end up seeing some kind of restrictions to the use of superchargers.
If the superchargers are intended primarily for long distance travel, perhaps blocking superchargers that are within 50 miles (100 miles?) of your "registered" home address? Or perhaps limiting the number of times you can use the same supercharger within a set time frame?
Or, possibly no use of superchargers for un-occupied cars unless you are logged into the Tesla Network (or whatever it will be called)
It goes against my grain to see any limitations, but on the other hand, if it gets out of hand, I would rather see reasonable limitations than see them go away altogether, and once Tesla has enough of a customer base, and high speed public EV connections are common enough , they will not really need them anymore as a sales differentiator. And I am SURE that as soon as Tesla figures they are costing more than they are bringing in (in sales), they will be looking at killing the program.