I think Apple should just drop the 's' designation and just give each iPhone a higher number (2015 - iPhone 7, 2016 - iPhone 8, etc.) to prevent any potential "same look, same phone" stigma of the 's' models. Maybe some minor cosmetic tweaks to differentiate each iPhone generation. Most people don't care if you tell them it's faster with a slightly better camera and maybe one other marginal new feature. To them it looks like the same phone they bought a year earlier. There have been some rumors of Apple considering just that. I know it's superficial, but for many, they want to have something that people can easily recognize as new, especially if they paid a lot for it. I know some will say just get off the 's' cycle, but that may not be easy/practical for some people currently on the 's' cycle. Maybe an OLED display with Force Touch on the iPhone 6s (iPhone 7 if Apple chooses to drop the 's') will have enough of an impact as the 's' model WOW feature. It's almost unnecessary for Apple to have a media event for the 's' models, just release a press release with the new, updated specs like they do with their MacBooks.