its interesting to look at keystone components in mobile. AFAIK it looks as though identity is the predominant keystone API . if you own identity then you are leveraged across both mobile apps and web.
The mistake, in my opinion, is to insist on connecting identities across devices, and across meat space and cyberspace. I don't have any answers, but do know that Kim Cameron's seven laws of identity[1] are the best story I've heard on this.
[1] http://www.identityblog.com/stories/2004/12/09/thelaws.html
Apple's fingerprint integration is convenient enough to be dangerous: once you enable it, it is hard to go back.
(Although actually to take a step back...owning the credit card channel still leaves the field wide open for the billions of people who don't have credit cards)