[jeroenhd]

Reading this announcement, the idea seems to be that FIDO keys will be synchronised across devices. That means you can lose your phone and still get access to your accounts from your desktop.

You might even be able to get access by simply logging in to your Microsoft/Apple/Google account on a new device if they implement this system stupidly enough.

[davidkhess]

Yes, these will be stored in cloud storage like iCloud Keychain. But I can go into my iCloud Keychain and delete individual passkeys - or I may have only one Apple device and then lose it. Or some malware clears out all of my iCloud Keychain.