I think ultimately it's going to come down to a paid, independent service. Startups can't offer this kind of thing for free as there is no trust involved in the transaction. Likewise most large companies have already traded away their trust capital for various fiscal and political gains over the course of their existence. No, there must be some legal recourse for the consumer for the moment the authenticator screws up, and the only way to transfer risk in that way is with money.
Probably the single biggest barrier to this is the widespread desire to remaining anonymous on the web. The thing it seeks to combat is precisely the thing so many value so greatly: maintaining multiple identities, personas, existences on the web.