No, no, excellent post. It's so well-expressed that I am going to use the points to shine light on facets of the "Hardware Sizes Only Plz" thesis. And I'm giving you a HELPFUL so don't throw things TOO hard at me either...
Yes, different strokes. But really, aren't over 20% of people going to have EITHER a job change OR a home move OR both within the ~8 year time you'd keep a battery? "Oops, looks like I won't be able to charge at the new job. Wish I'd bought a longer range battery. Wish there were a magic wand to wave to get more range from the same pack! That'd be of so much VALUE to me..."
And again, most college careers aren't going to outlive the battery's "career," either, and options that don't require recycling and a service visit (probably costing the same as a theoretical SW range-upgrade too!) would be a thing of value to both parties.
Others could opt to spend their money on Supercharger access at purchase, and spend for unlocking later when it makes more sense. Potato, to-mah-to.
Fair enough. But, they might not be!
There wouldn't be idle cells anyway. The limit in the software would be like the limits on a "classic" pack, which already keeps the "true 100%" and "true 0%" states of charge out of reach of children, uh, I mean, us.
We might be gazing into different brands of crystal balls, I agree cell-prices will keep going down but OTOH the savings in cost of labor to do a physical swap (and deal with evaluating the trade-in), the time and effort for the owner to get the car in for service, separate manufacturing configs, etc. make me think the flip-a-software-switch scenario is of a very high value to the company.