If Craigslist had implemented an authentication system that required a Facebook account in order to post to craigslist, THAT would be evidence of the trend you so desperately want to be true.
You can even generate a QR code using Xsync that will allow you to transfer money from your PayPal account to another person's, though that requires an added authentication step for security.
In the future, the phone or tablet will be used for multifactor authentication, obtaining up to five factors without inconveniencing the account holder: the phone itself (something you have), a PIN number (something you know), face recognition (something you are), voice recognition (something you are), and GPS (somewhere you are).