Comment by varenc

If you lose your domain, you have bigger problems than just passkeys. If you just used passwords, users would still have to somehow locate your new site and trust it with the password previously associated with your old site. Password managers won't input passwords from one domain onto a new domain.

As someone else said, you'd have to do an email blast and hope users trust the email blast as authentic to trust your new domain, and just someone phishing.

Loss of a domain is so catastrophic for trust that passkeys don't make it much worse.