Unlike the markets for model S and X, cars in this segment rely on enormous volume to be successful both product-wise and financially, and, considering what we know about Tesla and how hard it is to mass manufacture such a complex product like a car, it's really questionable whether Tesla will be able to pull this one off. The relative success of the (niche) model S is no indicator here at all.
Unlike some here on HN may think, the automobile industry, especially in this segment, is already a hyper competitive space and the existing OEMs have not only the infrastructure and experience building high quality products that people actually want but also a far bigger war chest to battle it out with. I don't think anyone (including me) is hoping for them to fail but im certain that this will be a pivotal point for the company on whether they'll truly be able to become a mass market manufacturer or stay a niche luxury player they are now.