If even one of the big three refuse to support attestation, then it's dead. And trying to retroactively force attestation at a later date will an even bigger headache than it would be right now.
It's not really a feature for normal passkey users as much as it is for enterprises / government who need to use vetted hardware (e.g. you can only allow AAGUIDs from FIPS YubiKeys).
They optionally can be all of the above, using AAGUIDs and direct attestation.