Whether or not this will be the case, remains to be seen, and yet there will be plenty of novelties to offset the eventual disappointment if higher pixel density doesn't materialize. These are rumored to be a new, 12 MP camera with Sony's RGBW pixel technology, a speedy A9 chipset, and the Force Touch technology for the screen that Apple employed for its Watch gear.
There might be other surprises in store, but the design is likely to remain similar to what we have now with the iPhone 6, or staying largely the same, save for the camera part. Check out all the imagined improvements in this master render of the iPhone 6s/7 in Jermaine Smit's concept video below. We particularly liked the home button back and forth swipe function, what about you?