That may be the case for you, but for many people it will not.
I'm pretty sure that I'm not alone.
I seriously doubt in several years that many phones will have many external buttons or controls. And the precedent is already set with the thinner iPads.
This is a complete other story. iPads don't ring and don't receive text messages.
If they kill the physical mute switch they should introduce a twice force tap with two fingers or something similar but EVEN when the iPhone is on standby. What I'm using often as well is the volume switch as a trigger for the camera.