I'd argue within 5-ish years you'll start encountering people who have never used a username + password combo at all.
Passkeys are the future - but how they will work across ecosystems remains to be seen (without a subscription)
Google has actually had support for passkey for many many months now, but for whatever reason, waited to formally announce it until just recently.
Cross-platform is also already solved. See the FAQ directly from the FIDO Alliance: https://fidoalliance.org/passkeys/#faq
LOL. This is not a serious answer.
But can one register apple/google account without password with fresh phone on setup screen? What would happen if that phone would die? Apple often asks for icloud password in various places (which really surprises me, I mean it's Apple app on Apple device which logged in, why ask me about it).
It still looks to me like master password (which is google/icloud password) and other accounts are accessible with this master password. Just less friction: no need to copy random passwords around.