Hell, a car with 40 kWh of usable battery capacity is still plenty for a high schooler to get around town or something. Which is what you'd often expect for a car as it reaches an old enough age anyway
Early Nissan Leafs started with 24 kWh, so when they lost a chunk of their initial range they became impractical to use. Your range might be shorter than the distance between chargers, especially in winter.
If you start with 40 kWh, you can lose a third of that and it's still fine for occasional long trips if you have charging network coverage. And you probably won't lose a third of your battery capacity ever, since modern EVs have battery cooling and better batteries.
LFP batteries will probably all outlive the cars they're in.
Those poor early leafs had no active cooling system for the batteries, being parked out in hot weather all day or doing heavy driving during the winter wasn't so kind to their capacity either
We have a slightly later leaf with ~30k but now it's getting older the range is only about 80mi in warm weather (much worse in cold). It's not really viable for distances, but we could hire an ICE for those rare occasions.
There's already a company positioned to take "dead" ev batteries, referb them and put them into municipal power storage. I'd guess it'll be the sort of situation where, if you can replace them yourself then the cells are yours to do with as you please, but if you go to a shop to have them replaced the shop will probably resell your cells.