Tesla is now officially supporting older S/Xs to be fitted with their 'new' 85kWh pack that actually has as much if not more usable kWh than the original 90kWh packs, but not quite as much as the 100kWh pack. The price is actually pretty manageable at $20K (and apparently falling), versus £80K+ Tesla want for a new S/X.
For some one like me who has a car that has FSD already purchased, it actually makes very little sense to 'upgrade' to a new S/X, but much more sense to effectively keep the car long term and when/if needed buy a battery pack from Tesla.
Interestingly the cheapest Model Ss are now sub £30K, the MCU2 retrofit is sub £2K now, CCS retrofit is £150, pay Tesla £20K for a new 85kWh pack and for £50K you essentially have a near 300 mile range S for an significantly cheaper price than new. Clearly the cheaper the used car, and the cheaper Tesla can drop the price of the replacement pack the more sense it makes to 'upgrade' the older car.
I have to confess I was very dubious if Tesla would ever offer an official battery replacement program, as when you combine it with all other upgrades/retrofits it does seem like Tesla is following up on their promise of ensuring these cars remain as sustainable as possible. Financially and commercially none of these upgrades makes any sense, as all existing manufactures essentially forces you to buy a brand new car every few years.
Credit where credit is due, if Tesla eventually offer an 4080 battery in retrofit for cars made in 2013 in 2025, that really would be an industry first.