Someone at the end of those trades has to do the replacement, which will dictate second-hand car value.
BTW, batteries wear gradually, and a battery with 70% of capacity may be annoying for a car, but is still valuable for stationary energy storage (for solar). To me that’s another optimistic factor that can reduce actual replacement cost.
This is literally a huge pile of batteries that can charge at any rate at any time. It can soak the noon peak of solar, it can sip late night wind.