I don't know why you guys/girls worry about this. It's not like a cheap DC motor with slotted commutator, it the slip ring type. I don't expect it needs to be changed for the coming ten years. If I have to change already after 8 years... so what? Don't buy a BMW if you can't afford the service. I trust them, after all, they aren't new regarding EVs. Also, as I understand, this design has some advantages also, so I am not worried at all.