Tesla has usually had an entry model for the Model S in the $60K range - which is currently the S60.
Even if many customers end up buying the larger Model S battery packs, having the entry model in the $60K range may be an important price point to hit - a starting point for people to look at buying the Model S - and then add more range/features from there.
Even after the Model 3 hits the market, there will likely still be a need for a $60+K Model S entry model - especially if Tesla continues to sell it as a software upgradable battery pack.