The traditional car companies will catch up with them (Apple was 5 years ahead of the competition at the time of the iPhone too for example), but by then Tesla will have over 50% of the world's battery production, and guess what all electric cars need? Batteries, and lots of them, and they will need to be replaced every 7-10 years.

Tesla right now does pretty well as a car manufacturer and the Model 3 will probably do well too, but by 2025 when the established car companies (like the German ones) have caught up, unless Tesla innovated far beyond those, it'll be a marginal car company - but a huge battery and energy company, as well as a "fuel" company with their supercharger networks.