Tesla's main competition right now is Nissan with the LEAF. They need to scale up and drive down the price of the Model S and 3rd model rapidly, or they'll get buried by the big players.
What they've done is great from a technological standpoint, but they need economies of scale to keep going.
You think a $50,000 luxury sedan with a 200-mile range, more interior room than an SUV, and a < 6s 0-60 time competes with a $25,000 econobox with a 100-mile range and a top speed of < 90mph?
I said the companies are competing, not those specific models.
Nissan's future plans no doubt include putting its electric drivetrains in cars like the Infinity G37/Altima Coupe, its mid-size Sedans, Murano crossover, etc, and they'll have a lot more production capacity (ergo economies of scale) and bigger R&D budgets than Tesla, so they'll definitely end up competing against each other. Nissan also has the benefit of being an established company with a good reputation; it will take a bigger leap of faith for the mainstream public to buy a Tesla, even if their 3rd model costs 30k.
Tesla started at the top of the market and Nissan near the bottom, but they'll no doubt meet in the middle and compete for the most lucrative segments.
What they've done is great from a technological standpoint, but they need economies of scale to keep going.