Simple idea for a tricky situation. We're obviously approaching a major transition from folding green stuff and payment cards (debit/credit with magnetic stripe) to new payment systems. What isn't clear is which of those new systems will win: NFC (near field communication, probably in your phone), QR codes, payment cards with chips in them, or Other. It's also not clear what is going to be happening behind the scenes, but I think it's fair to believe we'll be inventing something lighter weight than the existing schemes used by payment cards, ACH and so forth.
What this device is attempting to do is Be All Systems, so a shop only has to have one point of sale system and never have to worry about turning away a customer.
I don't know if it will work. PayPal did a deal with Discover so you could pay with PayPal (at some point in the future) wherever Discover card is already accepted, so there's a chance that we'll incremental our way through this morass. A lot of people are very reluctant to commit to any change before knowing where the Really Big Guys (Wal-Mart, Apple, etc.) come down. I, personally, think we need some legislation to happen before anything makes sense, but I could be wrong. The recent decision to allow merchants to kick some of the credit card cost back to the customer changes the landscape in pervasive and subtle ways that won't become clear for months or years.
But if I were a shop looking at POS systems, this one would be kind of tempting.