Tesla now offers a less expensive Model S. A 60 kWh version that employs a 75kWh pack which can be SW upgraded for $8500 at a later date. I think this is a good move. Probably lots of Model 3 line-waiters (and others) who want a new Tesla now but won't pay the $70k+ price. Those in line for a Model 3 but don't think they'll get the $7500 tax credit might jump for this as well.
This 60 is less than the original by $4k.
CNBC story here:http://www.cnbc.com/2016/06/09/tesla-is-bringing-back-the-lower-priced-model-s.html
Much as you suggest here, there is some speculation over at TMC that this move was because of the long line of Model 3 reservations: the idea is to bring back a more affordable S to give some of those people a chance to make the move to a Tesla now and, once they own one, Tesla likely has a repeat customer in the future.
Something that shouldn't be overlooked is that the new S60 should have faster Supercharging times than the old S60, similar to the S75, and it can be charged to "100%" routinely. [The fastest charging speed I've seen on my old S60 was 274 miles/hour when the battery was warm and below 5%, which is on the slow side by Tesla standards and, of course, the taper starts earlier on my older 60 kWh battery than it will on the new 75kWh battery limited to 60.] The battery also ought to last a bit longer since some of the eventual degradation will be reduced or hidden.
The new S60 should have a good trade-in value for Tesla since they can unlock the cars and turn them into S75 and S75D models for resale as CPO (Certified Pre-Owned).
Given this new development, I'd expect current CPO (used) S60 prices to drop by quite a bit in the next few months. In recent weeks Tesla had a big push to sell its inventory of CPO S60s at rather high prices (some high $40k but most in the $50k range). Now I know why!