1. Gigafactory will bring cheaper batteries.
2. Cheaper batteries means Model ≡ can be made affordable.
3. The "trickle up" effect means the luxury Model S gets the cheaper batteries, which allows Tesla to start putting in much more luxurious and higher margin stuff.
You'll be able to choose standard/large battery, standard/luxury experience, and standard/high-performance experience. There will be plenty of people that pick the standard/standard/standard config, but more options mean more margin opportunities for TSLA.
As an original owner of a 2013 Model S, I don't care about depreciation. Tesla is doing all they can to keep the CPO inventory low which keeps the demand/prices high. I didn't buy this car to resell. It's a 10+ year car for my family. Plenty of other people might worry about residual value, but it's not wise to buy a new car as an investment