I believe Android still has the option to use hardware attestation, but that automatically opts credentials out of cross-device synchronization, but Apple's veto alone is enough to make attestation non-viable.
If this can't make the "WebAuthN implies mandatory attestation!!" critics update, I wonder if anything can, and how useful their criticism still is.
And the sad truth is: Most people have no password manager at all. They are used to re-generate new passwords every time they want to log in! I'd wager that on some websites the vast majority of people are loggin in by pressing "I forgot my password".
Apple has also made it clear they have privacy concerns about attestation as well, which is also why they don't support it, but backup and syncing are clearly very important to Apple because that is very important to keeping consumers happy.
I don't get why this whole "they used to support it but removed it" is supposed to be an argument for anything.
More seriously, the fact that Apple previously implemented something and then removed that implementation gives us multiple pieces of information: they are technically capable of implementing it (not a huge surprise), at one point they thought that it was a good idea to implement it, at a later point they thought that it was not a good idea to implement it, they're willing to backtrack on implementation decisions in certain situations, etc... Depending on how you weight these different pieces of information, you can reach different conclusions about how likely reimplementation is in the future.
(Those extensions are for a Passkey manager to "solemnly swear" to an RP that a key was involved in some sort of MFA dance such as PIN unlock or biometric unlock and maybe a little bit of rough detail of what sort. Much more rough than Attestation details and not attested claims at all so a Passkey manager could lie about them, but that's enough for the sort of regulatory compliance or "due diligence" that many Banks might need from consumers to replace existing MFA logins with Passkeys. It is a relatively strong bulwark against attestation requirements for consumers.)
Do you have any argument for why they would add it back?