The real potential for mobile payments to go big is encapsulated in the brief reference above to mobile payments in store (Macy's & PayPal). The typical consumer won't really think about the inconvenience of the long line until facing it, making it too late to order ahead.

Furthermore, there's SO much to be gained by retailers from using technology like beacons in combination with an app that allows online purchasing (helloooooo Target?), that promoting an in store mobile shopping cart makes nothing but sense.

Macy's hasn't really taken this to the Nth extreme, but they appear to be a step ahead.

For a related article that focuses on this phenomenon, check out http://mobileproductstrategy.com/2015/09/03/why-blog-posts-speculating-whether-apple-pay-is-winning-or-losing-are-irrelevant-and-what-is-relevant/