I would hope so. It's none of their business if I buy a new device. This is plain respecting my privacy. BUT: If I can be sure that only my devices can decrypt

I would hope so. It's none of their business if I buy a new device. This is plain respecting my privacy. BUT: If I can be sure that only my devices can decrypt data sent to them and you know that my account will only announce keys to devices I actually own, then you don't need a notification when I add a new device because however many devices I have, only I will be able to read your messages. Of course because we can't trust apple to not silently add more keys to an account, all of this is moot anyways.