I got a theory: it is getting harder and harder to show a markably new stuff in every two years. let's face it, there are plenty people who buy the new model year after year, but the most people changed his iPhone for a bigger one. 3GS, 4, 4S -> 5, 5S -> 6, 6S, 7 now there's no reason to enlarge the models even further, but this is why it's reasonable to release a new size between 4.7 -inch and 5.5-inch (and maybe a 5.8-inch Pro version to replace the Plus). but the substance of this theory in a nutshell is: the development in the high-end smartphone industry necessarily slows down (just a little, one third), so the size of the group of people, who year after year seeing the new models can still loves their 3 years old iPhone, is constantly growing. good for Apple, because these consumers stay in the family, but the other side, Apple has to change the 2 years circle to 3 years as intel did: process-architecture-optimization. what do you think?