Anyone arguing about audio and getting stuck on the overall hearing range of humans is actually missing the point.
What digital audio has really been doing is giving us lower resolutions on the sounds we can hear.
Have you ever had a car radio with a dial that won’t go to the exact volume you want? The ‘chunks’ are too big to get it exactly where you want it? That’s a lack of resolution in that volume knob. Put that lack of resolution throughout every part of the audio program and the overall effect is perhaps not easily heard, but it seems to be easily felt. – Excerpt From Save The Audio
HD audio is really about the resolution, not the frequency range. The color’s won’t be brighter, there will just be more of them available. Having more available means you leave the computer to guess about less.
The whole “no one can hear above blah blaah” is just a diversion from the fact that we can all hear and do indeed miss what the computers have been removing from our music.