Why do you think 99% of the new Tesla's today will be in a scrap heap in 20 years?
This may well increase with electric cars being more reliable, but other failures (rust, collision) won't change much.
So 99% is too high. VEH1107 shows that 22.5% of cars in the UK were 13 years or older.
[VEH1107] https://www.gov.uk/government/statistical-data-sets/vehicle-...
The cost of replacing an old battery pack quickly exceeds the value of the car. You might be able to get a few extra years refurbishing it but that’ll be expensive and require niche battery work that’ll be hard to find.