Perhaps we will find out, if both Apple and Starbucks do introduce retail payment systems. One might speculate that the firms will take different tacks.
Apple might be thinking about creating a mobile point of sale system using iPads. Starbucks already has an investment in Square, so that approach seems less likely for Starbucks.
Instead, Starbucks might only be thinking about ways other retailers can be incorporated into the Starbucks mobile payment environment.