This is kind of a good thing...
On the plus side, you don't need to carry your wallet, but just your phone. Which is more than a phone. Its your GPS locator, your music box, your personal tv and web device, your PDA, your camera ... all rolled in to one. And if you want that nifty online purchase? Your phone already has that trusted information built in. ;-)
Forget about cash, you have your payment card, which incidentally means you'll be more inclined to spend more money because you lose touch with how much you're actually spending. (If you only have 20 quid in your pocket, you tend to spend only quid. If you have your entire bank account accessible, you tend to spend more.)
Now when someone steals your iPhone, they not only stole your phone, your PDA, all of your personal data, including access to your facebook account, but now your bank account and you don't even need a PIN code. So you then need to set up multiple banking accounts where you transfer $$ from your real account. So you may put $500 dollars (US) a month automatically on the card. Then if you lose your phone, you are at risk for at most $500.00. Assuming that once you report your iPhone stolen you are no longer liable for things purchased on it. This will make banks happy because they can now charge you more in fees or have an account that doesn't pay you interest so they make money off the deposits.
You see, now the crook doesn't want to steal your phone because its nifty new tech to be resold, but rather as a way to rob you of your money.
I'd worry more about snatch/grab robberies than someone going high tech and scanning data from the NFC device.
But what do I know?
I'm the tech guy who likes new tech, but is still paranoid.
;-)
Mine is the jacket with the foil lined pockets so you can't read my RFID enabled identity card(s)