Who is going to carry around, let alone take out their iPad, for POS payments?
I remember when people used to say "who's gonna take pictures with an iPad? Putting a camera on it is pointless." Yet here we are, at a place where it's increasingly acceptable for someone to whoop out a full size iPad and snap a picture. People carry their iPads and iPad minis with them everywhere they go nowadays so having this functionality isn't as far fetched as it might sound. Besides, apple pay works in apps too and don't be surprised to see it starting to gain more and more functionality. Off the top of my head I can think of it being embedded in actual websites and used to transfer money from one person to another a la PayPal.