Apple have filed a patent looking at NFC but hinting at iBeacon (a variant of bluetooth) to complete the action.  The secure element in the pic below could be the digital wallet.

Apple Investigating iBeacon-Assisted Mobile Payment Methods

Patent application number 20140019367, filed in September 2012 and published today, describes a method that would send payment data through various wireless interfaces without compromising the user’s data. The method uses two links — one connection to a point-of-sale device to establish the initial connection and a second, secure connection that sends the payment information. This payment information is then processed by a backend server, which uses a shared secret to verify that the connection was secure before it authorizes the payment

 

Apple even notes in the patent that NFC "is less desirable for longer transactions," while Wi-Fi or Bluetooth has "more desirable characteristics for maintaining the link over time than NFC."