I'm sure Tesla will also have EVs as good as Tesla for half the price by 2020. They'll also have a vastly improved super charger network, a mature software ecosystem, a mature direct sales/servicing model, and whatever else they dream up like Powerwall and other systems that can potentially add value to the whole. VW will just be scratching the surface by 2020 while Tesla will likely continue sprinting ahead.
When EV gets popular enough won't all petrol station install chargers too? When this happens the super charger network will not be a large advantage. The only issue I see is if each company creates it's own "super/fast" charging system and DRMs it for "security" reasons.
More importantly, when EVs get popular we'll obviously see new power supply stations everywhere, and they may not comply with today's notion of a gas station. We'll see for example EV-specific stations such as rest areas or highway diners or shopping centers or autosilos or private parking spots that provide that service while drivers go on with their lives. These actually already exist, but as the number of EV cars is so small in comparison to ICE cars that they are barely noticeable.