I, like many others, have been all indignant about paying for a feature in 2018 (I paid for FSD separately from EAP) with no delivery as of yet but plentiful broken promises. I have also been insistent since after end of 2019 that I would never buy FSD with a new Tesla again, and that opinion has only been validated by the ridiculous price increases, the addition of the subscription model, and now the lack of HW3->HW4 upgrade path. I would be shocked to hear that any rational person having done just the slightest due diligence is buying FSD with their new Tesla at this point.
All that said, while I love my June 2018 Tesla M3, I am beginning to contemplate what my next vehicle may be. For various reasons I have developed the need for a larger (and higher) car with a more cargo room, but I have no desire for a truck or giant SUV as my primary vehicle. A 2024 MY is a distinct possibility, despite feeling somewhat burned by Tesla on the whole FSD debacle. But if it comes to pass that continued autonomous vehicle development, with a goal of, say, true L3 on highways, will only continue on the HW4 platform, I would probably take advantage of a program to upgrade my HW3 vehicle to a new HW4 vehicle if Tesla would let my FSD purchase carryover to the new vehicle.