I predict that they would miniaturize the entire NFC and bluetooth chip/circuitry necessary and embed it completely inside the Watch to make it stand-alone so it will not be dependent on an iPhone or any other device. That might not happen until iWatch 2 or iWatch 3, tho.
The watch already has Bluetooth and NFC in it. What it lacks is a data connection. Adding that would be problematic for both size and battery life.