I've been thinking a lot about this so I decided to shrink down the iPhone 6s and "redesign" the home button. The new home button is a pressure sensitive software button. It will work just like 3D Touch. The Touch ID sensor could be rectangular to make the sensor at least as large as the circular one. The main advantage of this design is to make the iPhone smaller while retaining the same screen size. The new home button can probably be more durable than the physical button. What do you guys think? I hope you will appreciate my paint skills.