That would depend on how many people were buying the Model S simply because it was the only Tesla sedan available at the time. The more you add premium features

That would depend on how many people were buying the Model S simply because it was the only Tesla sedan available at the time. The more you add premium features like performance mode and dual-motor to the 3, you increase the chance that someone who was considering the S might down-grade to the 3. Even today, if you want a Tesla sedan NOW, you need to buy an S (or an X, if you're looking for an SUV). Once the 3 burns through the existing reservations (which I suspect may happen fairly quickly, given that many people will choose to hold out for the $35k unicorn), then new buyers who want a car within a period of weeks will be able to choose.