The absolute dream is to have a single nonprofit OAuth identity provider against which people can prove their identities with FIDO U2F, then use the issued toke

The absolute dream is to have a single nonprofit OAuth identity provider against which people can prove their identities with FIDO U2F, then use the issued tokens to auth with services of their choosing. Building this network is incredibly hard, though (what website would accept an identity provider without any users, and what users would use an identity provider not accepted by any websites?) so the most popular implementations are hosted by Google or Facebook - but there you have all the obvious privacy issues.