Tesla can't retroactively change the warranty on a vehicle. So you still have the 8-year/unlimited mileage warranty you have always had.
The new 8-year/150k mileage warranty only applies to new S/X vehicles sold after Tesla made that change to the warranty terms.
Well two things, the first is that Tesla can, and has, retroactively make the warranty better. They just can't make it worse. So were it the case, for example, that my battery completely failed at the 160,000 mile mark I could rightly argue they have no right to make my warranty worse.
The second is that I will readily concede that I just assumed the new warranty was intended to be retroactive although I can see the mistake in that since it is, in some scenarios, a downgrade. I'm sure it's moot as they'd probably say the battery hasn't really degraded and it's just being software limited for my protection.
In any event I'm glad people (or at least 1 person) is doing this service I'm just not ready to jump at it.
Thanks for the correction.