Regarding Teslas announced 2017 Supercharger plans: I am starting to see a pattern here, with Tesla expanding existing California Supercharger locations. This isn't the only one that is being expanded. We know that Barstow, Dublin, and Rocklin are being expanded as well.
And that seems like a smart way to expand the Supercharger network: doing deals with the property owners they currently have agreements with to expand an existing site as opposed to finding a new site to build a Supercharger.
Yes, there are still "holes" in the Supercharger network that need to be filled in. But in many parts of California there are no holes, just not enough charge pedestals at a specific location.