Non-CPO cars will be the ones most affected, as the warranty that comes with CPO cars is a key selling point. Private party and third party cars need to be discounted accordingly.With poor reliability ratings, used Model S prices are going to have to drop or Tesla will have to increase the warranty.
Hopefully around the time the 8-year battery and drive unit warranties start expiring, there will arise independent repair shops capable of fixing them. Or Tesla will get the repair costs down. This will need to happen sooner or later for the Model 3, anyway.