Tesla needs a volume car to build a solid revenue stream. If they don't come in somewhere in the mid 30"s, that could make it tough for them. Look at Mercedes and how they have grown their lower cost cars. It gives them the ability to go all out on the top line models because of the cash that the 200 series gives them. I could see the Model 3, or whatever, starting in the mid 30's and optioning out to the 45 range. Look at every other premium car builder. But they won't be able to afford the level of support they now offer for the Model S. They will need to be very careful to differentiate between the two without cheapening the Models S/X (high end) or killing themselves with service costs on the cheapo models. Lastly, battery cost will drop precipitously as battery production volume grows, as it does for every new tech. Elon's strategy of opening up patents helps them to get there. Clearly, that is the main reason he did it. He NEEDS Toyota, GM, Ford, Mercedes, BMW to get on board as they will be the ones to lower cost through their ability to crank up volume based on their size, engineering size and wealth.
This development model has been repeated over and over again since the mid 1800s with the battle of John Deere, International Harvester and Ford. The news guys innovate, the big old guys develop and expand. Tesla's challenge will be to stay relevant as the big boys try to take over.
As an investor and a owner (on 9-26, dammit!), I think they are the right track.