Oh I see, Thought I was missing some part of that. Still not sure that will happen - I just expect devices will operate on more and more frequencies - as is happening with cellular networks. The Iphone couldn't operate on O2's 4G frequency but they just made the device able to use that aswell.
Im sure the clients operating on 2.4 will reduce and 5 will increase but as devices increase Im still sure we will have AP's that operate on something like tri-band then quad band in order to satisfy more BYOD's etc. But only time will tell on that front I suppose :-)