Considering that the iPhone 5 was a non-update (if any other OEM released an update like the iPhone 5, they would have been the laughing stock of the world), I can imagine that Apple will finally unveil dramatic changes on the iPhone 6. Apple probably knows that they got lucky to survive with the 5 because people will buy it like crazy none the less, but that it would be dangerous to play chicken and unveil the iPhone 6 as the (iPhone 5 + NFC & 720p) in case people finally wake up from the "distortion field".
Maybe Apple will finally pull out all the stops from a technological standpoint and really raise the bar in order to solidify their market share. At least, we should be seeing NFC and real HD screens instead of the illusion of "retina display".
One thing is for sure, if we don't see a large screen iPhone, I will be in disbelief, but Apple will probably sell tens of millions instantly anyway. The iPhone is still held as some kind of status symbol, and the general public is uneducated about (superior) alternatives.