Eventually we'll cease to see quill-stems being produced at all, except as vintage and collectors items. It's like debating drum vs. disc brakes, many people were resistant to the advance and progress of technology.
Oh PLEASE. Not everyone is a racer. The run of the mill rec rider could hardly give a bigger **** about miniscule "stiffness" benefit. Just because racers use it and abuse stuff doesn't mean the rest of the world needs to run the same gear they do.