Today, Apple pulled back the curtain on their fall hardware refresh that includes a new Apple TV, Watch and a couple of new phones; you can read Paul's post about all the new stuff here. But one thing that the new iPhone X is attempting to do is to change the behavior of user which is not a trivial task and is likely the biggest 'risk' Apple has taken with the phone since its introduction.
Let me explain. When the iPhone was first announced with its one button navigation, it was a stark contrast to other devices at that time. Over the next 10 years, Apple slowly evolved the button with new features by adding Siri and Apple pay but at the end of the day, the navigation stayed the same; press the button and get back to the home screen.