Well lets see, i buy a Tesla with an 80kwh battery. That gets me 265 miles, but after 8-10 years it will lose like 20% range. (Give or take). That's the big question, "how long will the battery last".
But i propose that buying a car with a battery pack that is your only battery for THE LIFE OF THE CAR!!, is old school, old style, legacy thinking.
That battery pack, can be popped open, and the battery cells can either be reconditioned, replaced, added or removed
As the range can increase by 8% per year. In say 8 years, when a new gen 3 gets printed, (kidding sort of), THAT car will get 64% better range!!!!!! So on a summer fuel free road trip with my 8 year old model 3 all my friends driving new model 3's will have to wait for my 'frequent' charging stops, or they could just leave me in the dust.
To me that sucks. Its like if you could only buy an iphone every 4 years. It only takes one year for a phone operating system to be 'old'.
I would like to suggest that the phone OS is analogous to the battery in a Tesla.
The rest of the car changes in design, features etc. You can't do much for a old model on that score, but the battery pack, if not resized for each model, is something that could benefit a driver/buyer immensely. Imagine if the model 3 you buy in 2017, with a range of 200 miles, in 2021 can be swapped for a fresh battery in 8 minutes, that will give them AN EXTRA 64 miles.
If the packs are built with some space for more cells maybe you can upgrade anytime you want.
It might cost labour, and the new cells, plus the trade in value of the cells of the original pack.
This will grow an after market industry which can use Tesla OEM cells to upgrade and repair Tesla's battery packs.
Perhaps Tesla wants to own the battery packs and rent to own them, or some other financial instrument of ownership can make it a viable reality that would see Tesla packs come home to roost and be upgraded and repaired. The buyers just come every 4 years for a new top of the line state of the art battery pack, and able to take advantage of the lighter weight or increased range the new generation cells provide.
It may even be possible to take 6-10 grand off the cost of the initial purchase, and owners would pay a battery maintenance program that would guarantee them the 4 year upgrade plan.
This way, our car can always be able to take advantage of the newer power cells, and this will also keep the resale value up for the car.
Alternately, hopefully, every 8 years we can trade in our battery and our 170 mile model 3 will get upgraded to the 370 mile pack ready for another 8 years.
Just an idea.