Biometrics devices are expensive toys so far. There hasn't been a serious easy of use device made yet that uses biometrics for authorization. Especially something that you carry around with you at all times, like when you're out at the bar scene, in a concert venue, or a freezing night.

The real hurdle to mass option is consumer protection. That is what made paypal big and until the average joe has confidence they can reclaim funds from an entity who didn't perform their side of the deal cryptocurriences will be backroom currency.