If FSD comes in 8 years to AP2 (a big if too), do you really think someone will be willing to pay $20K extra on a car worth probably $20K, if that (will need a new battery, everything out of warranty, could be not even worth that)?
Wrong. Confirmed by companies such as Waymo and independent researcher such as the study from Stanford that you don't have to be a tool to be killed by Level 2/3 driver's assistance features.
Robot Cars Can’t Count on Us in an Emergency
You would just buy a new car with the $20,000 FSD option.
Old car, the hope is you get $3,000 worth out of FSD features before its dead.
If the car has a steering wheel - you should not be killed by L2/L3 autonomy and it is your fault always.