This is what will most-likely happen. A future major iPhone release (hopefully the next one) is going to feature mostly "camera" upgrades: higher megapixel, videorecording, and perhaps a front camera for conferencing. After all, what else can future phone models offer that's NOT doable with just software? There's not much to physically change, honestly. GPS is already here, it just needs the right software. We don't want a smaller phone, as that will impact the screen size. Capacity upgrades, sure -- but most people don't care enough about that to update their phone (and with apps like SimplifyMedia - it's not as important anymore). Different colors/new look? Not "big" enough.
So camera functions are sure to come -- Apple just needs the current phone to run its life cycle first...