One of Apple's most valuable, yet often dismissed, traits is that they refuse change for change sake. This approach requires the most discipline but often yields the best, most enduring designs. Apple is a forward thinking design focused company and I would expect the iPhone 7 to look as the leak suggests. While the rest of the industry finally feels like they have caught up to Apple in terms of design, they're about to be left in the dust again for one simple reason.
The vast majority of people use a case and the iPhone 7 looks to be a phone truly designed with a case in mind. The camera bump looks to be about the same thickness as an iPhone 6, a thickness most people claim to be ideal and would flush the camera to the case. The design team have a wide range of experience working with different materials and recently tested making a first gen battery case, you know what they say about first gen Apple products lol. The smart connector, perfect for powering ever more advanced cases.
I bet Apple is going to focus on designing a range of cases of such fit, quality, and functionality that they will begin to recede and become a part of the iPhone's design itself. Apple has the talent to pull off case designs that feel as if they're part of the phone itself, not a case.
This is the next evolution in my opinion and why they continue to make the iPhone ever thinner. Soon, a phone's thinness will be increasingly judged by how thick it is in a case. It's sort of ironic but the thinner you make the phone, the more you can cram into its case. Be it a battery or something else entirely. The thinking being if people are going to opt for a case anyway, might as well make it great.