Bingo!
Linux will never be a big desktop OS on PCs. Windows and Apple will be the dominant PC OS.
However, as we’re move away from PCs to other devices (tables, phones, etc...) Linux will be a major player, but I’m not sure most users will even know it.
Android is just a flavor of Linux.
Most non-apple tablets run some version of Linux.
The Nook is a Linux device.
The Kindle runs Linux as its Os.
My guess is Linux will eventually become huge as a personal operating system, just not on the PC (and most people will never even know they are running Linux).
I think its going to move up from tablets to the desktop. With many functions moving to the Cloud it is not really relevant what you run on the desktop anyway.