We are currently conceptually iterating a user experience for a forward looking network of vending machines. The idea is the user buys food via smartphone app, pays via that, turns up just to pick it up (or a proxy delivery company comes and does it for them). So there's ~zero physical interaction, no cash handling, and like 10 different ways to pay, from digital currencies to credit card gateways to appstore in-app payments. We are very seriously considering completely avoiding NFC/contactless/stored value payment cards, which would essentially negate any requirement for payment hardware or related programming.