For instance, now that Prime is set to become the new Whole Foods customer loyalty program, it's probably safe to say your grocery purchases will be tracked the same way Amazon tracks your purchases online, so it'll know what, when, and how much of any particular item you buy. This will allow them to not only target deals specifically to you (e.g., send push notifications to your phone when something you buy frequently is on sale, recommend items/pairings similar customers purchased, offer freebies, etc.) but also entice you with a nominal discount to set up "subscriptions" for things you buy frequently, much like Amazon.com already does.
In theory, Whole Foods could allow you to simply set up recurring weekly basket of perishables like milk, eggs, and various produce, prepay for it, and just pick it up from an Amazon Locker on your way home from work, or on your way out of the store after browsing for whatever other ingredients you might be in the mood for that week. The possibilities here are huge.