well technically U can with Iphones but ya, the "update" would cause so many new problems and may even slow down or shut down the iphone/hw3 completely. Just because U can force update on an antique DOES NOT mean they should.
But the Hw3's dont want to let it go, there comes a point where it becomes pointless , so much frustration, time, effort goes into the fixes and still has problems.
Their efforts become futility just to appease the early hw3 owners HW3 has had a good run, its amazing they still even receive updates.
Now, I state the above so that history does not repeat itself for early HW4's. Why they even bother with 4.5 is silly. Hw5 has enough room to expand for a few years. I doubt we will see a hW6 in a future car but who knows but offering a half the power of an hw5 is counter-productive.
FSD level 4/5 will never work in an hw3-so why try. Answer to save a few bucks, avoid a class action lawsuit, and tons of bad publicity.
The only viable option is to offer a discount on a newer HW5 car..........the alternative is massive payouts to all those people who joined the class action.