Disagree. Because there shouldn't be an expectation the iPhone design has to change year over year. Furthermore it's not logical for Apple to change the iPhone design on an annual basis, which they know will generate revenue using similar components . Which is maybe why they used the iPhone 7 model another year, because more drastic changes coincide With an overhauled design. Just because Apple didn't take the same approach as they did with the iPhone 4 from the 3GS, from the 4s to the 5, why should they follow the same pattern every year? When you factor Enough technological advances, the iPhone usually changes in form along with those advances, similarly what's intended for this year.
Look at the broader spectrum, Apple doesn't physically make overhauled changes to their hardware lineup every 18 months or so. Most of their hardware resembles earlier models, its just a lot thinner. For example, The iPads are primarily the same as they've always been from There origin, they're primarily just thinner and other minor hardware tweaks.