In the worst-case scenario in which users defer to some weak/centralized system, how is that categoricially worse than the centralized systems we already have?
Humans are bad at this which is why we recommend password managers.
That said, I do think keypairs are the way forward, I just also think they need either strong integrated software support in whichever device is being used, or strong external hardware support.
(Yubikeys are nice because they kind of extend the “key” metaphor that people are already used to, but I wish they shipped with a paired backup key that was provisioned with the same key material. Maybe colored red to distinguish it.)
Two identical keys, is less secure, for those who would otherwise have bought many different keys.
If you instead buy two different keys, then, when you lose the first, you can know it's safe to continue using the second one. And you can block the first one, without locking yourself out.
Maybe getting two different keys would be a good idea
Yes, two different keys are more secure, but they have some pretty severe usability problems.