The point-of-sale terminal would transfer the payment information to the phone and the payer would just need to check the payment info and accept it by pushing the OK button. For larger payments the payer would be asked to confirm with a PIN number. It seems also likely that phones will be equipped with some form of biological recognition capacity.
At the same time, all else equal, the recovery in labour market conditions that has occurred should support faster nominal wage increases, as has already been evident (albeit only to a moderate extent) in the course of this year. Taken together, these forces suggest that cyclical inflation forces will be subject to push-pull dynamics.