If your Tesla vehicle with FSD is totaled, the cost for the replacement physical vehicle, physical options (PPF, ceramic coatings, floor mats, racks, etc) on the vehicle, FSD and other software is an issue between you and your insurance provider.....
That said I would have a real hard time paying $12k for FSD unless it was really proven level 5 and it was transferable for at least 10 years if my original CT is totaled.
You have to make sure you buy insurance that will replace your physical vehicle, physical options on the vehicle, FSD and other software.
FSD transferable is not a Tesla problem.
Getting full replacement cost is an insurance feature or option you have to buy.
If you want you need to verify it is covered before you buy the insurance.
This issue regarding replacement of software is not new and is not unique to only Tesla.