Finally chiming in after reading through this thread. I'm now resigned to the fact that I can't QUITE afford Model S, so I'm now targeting BlueStar (with the wife being on board, which she isn't for the pricier S). My current car will be 10 years old then anyway. Thus, I've been thinking a lot about this car and have a few thoughts:
-They'll have to build it out of aluminum, right? Sure it's pricier but they almost have to for the lighter weight and its effect on range. They will also be very invested in aluminum with S and X, anyway.
-Assuming current battery chemistry, I suspect they'll offer ~40Kwh and ~60Kwh similar to S, which will take this car a bit further given its smaller size. Probably ~250-mile range out of the big battery. I don't think they'll offer an ~85Kwh, as I just don't see Tesla besting their own luxury model in range.
-As AnOutsider and others have said, I think they'll stick with the touchscreen interface, but likely a smaller display. I agree with 15". Their enter driver UI is built. They're not going to throw that away for mechanical knobs and buttons just to make S look more luxurious. They've spent years and a lots of money building a platform. They'll leverage it, and it will become a signature Tesla thing.
-Besides the car being smaller, I think BlueStar will lose a handful of luxury items that S has, like the panoramic roof, air suspension, retractable door handles, power rear liftgate, electrochromatic side mirrors, and the premium audio system likely won't be as good.
-I suspect there will be a Performance version, a la Lexus IS F or BMW M3. I'm hoping for 4.9 or 5.0 or so 0-60 on it. Quicker would be awesome, of course, but again, I don't think they'll get too close to the S Performance.
-17" (standard) and 19" (performance) on the wheels, IMO.
-Finally, the name: Just a guess here, obviously, but what about Model E ("everyone" -- could be useful in the marketing campaign)?
Who thinks they'll do a Signature series for this car? The only reason why I question it at all is because it's the mass-production, mass-market car, so maybe they won't do anything that special. But if they do, I hope to be on the Sig list.
Hopefully Franz makes this car as sexy as the S is.