Obraik:
An iPhone battery only has one cell. An EV has many hundreds of cells, which the degradation is spread over. So a Leaf might have 60% SoH for the whole pack, but each cell is not that low. There will be a point where yes, the battery is effectively dead but I haven't heard of even a Leaf getting to that point yet.
But if some cells are close to the threshold of the acceptable limit, then wouldn't that mean that the other cells are getting close to that threshold? i.e. the deterioration of the pack accelerates as it becomes more worn?