It doesn't matter whether it can't ever be ported back. It doesn't work today, and that's all there is to it. Musk lied. And it isn't the first time he does so either.
[1] https://en.wikipedia.org/wiki/Development_of_Windows_Vista
Windows Vista and software in general are not even remotely comparable: they are not sold today with the promise of features tomorrow - they are generally sold when they're ready. Even pre-order games are usually refunded if they incur too huge delays or ship with significantly altered features (see Cyberpunk 2020).
Just like you can't be a little bit pregnant you can't have a little bit of FSD. You either have it or you don't. It's a boolean, and it's embedded in that word 'full'.
Okay, compare accuracy of MobileNet to ViT. ViT has 90.45% accuracy and 1.843Bn parameters and MobileNet has 79% with 5.47M parameters (2020, v3 is 75% with 5.4). [0]
These two networks are nowhere near equal. If you could put ViT on a phone and run real-time inference you would. But you can't, so you take a major cut in performance to get what you can.
There are multiple metrics you need to look at when evaluating networks. "Being able to perform on a dataset" is not even that useful of one.
[0] Have fun https://paperswithcode.com/sota/image-classification-on-imag...
Are you saying that the possibility is enough to prove they didn't cheat people?
If, some day, Tesla hypothetically says "we have determined it is technically possible to backport FSD, but we aren't gonna, because we like making money, not spending it" is that enough in your mind to demonstrate they didn't defraud anyone way back when?
Or do they actually have to make it run to fulfill the original promise?
That said, if it doesn't happened this year, it doesn't mean it will never happen.
The first problem they need to solve is FSD. If they can't solve FSD even with latest hardware, then well, that would be bad on its own.
The question is, what happens once they solve FSD, do they port? Maybe, I don't think it will be nearly as hard. Now realistically, it's probably cheaper to give free upgrades to everyone and not have to do the port. To me that feels fair, is like "hey, I promised you FSD on HW1, is gonna be a pain to port, but here, take this free HW upgrade", I'd be OK with that.
Now if they don't compensate HW1 users to some degree once FSD is solved, I do feel that would not be cool.
But my point here is that, we are jumping to conclusions, we don't know yet. We can't claim (yet) that FSD will or will not happen.
To give you an example, ImageNet for image classification required for many years a descent computer and GPU to run inference. Today, an improved version called MobileNet, runs in phones with no GPU from advancements in AI training with half-precision and why not.
So, how can we be so sure that FSD can't EVER be ported back to HW1?