My son had the iPod Touch 5th or 6th gen version that had the 16:9 screen with the same size as the iPhone 5/5s/5c/5se. It was super thin and yet Apple managed to fit the headphone jack in there along with the Lightning connector and speaker. And people accepted the camera bump, and the iPhone 6/6s have camera bumps (I think they look tacked on); going thinner on the next iPhone probably means a bigger lens bump.
I would like to see more of a sculptured appearance, but that might be too polarizing. The Galaxy S6/S7 Edge models with the screen that curves around the sides of the phone may not be easy to hold but it does looks cool. I hadn't originally planned on getting the iPhone 6 because I really liked the screen size of the iPhone 5s I had, but since I've owned the 6, I find it may be the sweet spot (as far as I'm concerned) in the compromise between screen size and wear-ability. Of course, with Apple Watch, aren't we supposed to keep our phones hidden away and just interact with our true wearable?
I'm trying to make it over two years between iPhone purchases, but I know that my son is getting a new phone for freshman year at college. He's using my iPhone 5 that I got when it launched in 2012, but I've already had to replace the battery and screen. Four years for a smartphone is forever. I don't think whatever Apple is releasing will come soon enough that I upgrade my 6 and hand that down to him, so he'll get a new 64 GB version of either the 5se or 6. He gets to pick the color, though!