Prior to experiencing WDW's Magic Band system, I was not a fan of NFC payment systems. I now find myself bizarrely evangelical. Whether you get into a Disney park on a band or with a card, you are using NFC/RFID. While the room charge feature is obviously only available to people staying on property, this isn't anything obvious stopping Disney from asking anyone entering the park to supply payment information, as a way of letting everyone charge things to their band. This would essentially reproduce the online payment model (stored default payment method, whether on PayPal or Amazon or whatever) in the Real World. As a side benefit, it would allow Disney to deploy EMV systems ONLY at the gate, rather then at every single kiosk in the park. If they took this idea to its logical conclusion, they could even remove cash completely from the park; you could "load" your account (not your band -- the band is just a token to access what is in your account) with folding green stuff if you wanted to, but only at specified locations, rather than, again, every single kiosk in the park. Folding green stuff and coins have significant costs and risks; eliminating them would be a big deal. If Disney could roll up _everyone's_ scattered charges throughout the day to one bigger charge at the end of the day (a la the iTunes model, where if you buy several things over the course of a day, it bundles them up in increments of around $10), it could save on interchange fees.
It's less clear how NFC could be deployed more generally. Obviously, any institution (hospital, university, large corporation) which serves enough people consistently will be motivated, over time, to deploy this kind of system. And it's not hard to imagine chains like Starbucks, Dunkin Donuts or McDonalds which already offer reloadable store cards and associated mobile apps going down a similar path. The ability to offer non-cash payments without the massive fees associated with small charges is compelling for large chains.
These kinds of systems have the potential to push the world even further in the direction of chain standardization. The single-shop and small chain is going to be a tougher nut to crack.
And while it's easy to wear the Disney band on vacation, I don't want to have a whole bunch of bands. If NFC payment takes off, it's either going to be cards in a wallet (since we all do that anyway), or we'll need a device flexible enough to represent all the different NFC standards.
Cue paranoia about people stealing your data or stalking you -- then think about how amazing it would be to never have to worry about misplacing your kid on vacation again. Not to mention how fabulous it would be to lose your payment media, be able to turn it off within five seconds, and activate a new payment form a few minutes after that.
ETA: A humorous opinion piece on NFC and SmartWatches: