It certainly is a difficult sell to the average user. For most Internet Banking, it's already implemented, but try to get users to accept that when using Facebook or access to their mail.

In Denmark we have a public system called "NemID". It is a 2-factor authentication, which relies on a card with one-time codes, or eventually, a physical key-generator. It is used to anything related to Internet Banking or access to the public services on the internet, such as application for university, change in tax return, and the like. Unless you can incorporate such a system, which ensure that most uses already have the needed physical token, I not convinced you can pull it off.