That's a price for a 85kWh supercharger enabled battery. The price that they sell 60kWh batteries does not matter because there are so few of them. Now with 70D all new cars are supercharging enabled.
If you are using the archived thread above as your reference, it does not support your assertion the $45K cost is for "
a 85kWh supercharger enabled battery".
That thread contains the keyword
$45K exactly 4 times. None of them refer to anything other than he cost of am 85KWH battery. No qualifications.
That thread contains the keyword
Supercharging exactly 2 times. Neither of them is in reference to a replacement battery.
Does this mean you could use a 3rd party battery in Tesla? I doubt that will work.
Technically, it's possible provided any signals/protocols/etc... were reverse engineered and implemented correctly. You'd be able to drive with it.
If your point is that supercharging wouldn't work because of it being a non-Tesla battery, if the above implementation was such that the car accepted it to drive and "normally" charge, I'd expect it would supercharge too.
Again, I've seen no evidence to suggest that the Supercharging is enabled within the battery itself. There's lots of evidence (ncluding screenshots that have been posted here) that the car's computer is what maintains a configuration database for all of the car's options.
That is a very good point but I still think they cannot afford to pay for our electricity forever. I think we'll be seeing upgrade offers, for example from 85kWh to 100kWh battery. I think people are willing to pay a lot for the upgrade and Tesla can sell the old 85 battery for home storage use or something.
Folks have done the calculations using "reasonable" Supercharger usage, and the up-front charge can pay for a significant amount of electrical cost. All that has to happen is for the average to work out within Tesla's financial model. There will likely be some outliers that supercharge more than than what their initial $2K covered. There will also be those who barely use it.
Finally, once Tesla has solar generation in play, the financial model takes another turn in their favor.