"One OS"?; wouldn't that be Linux? Linux already runs on everything from smartphones and embedded systems to supercomputers. In fact, Linux is probably the most common OS in the world, except on the desktop (and I don't think that is likely to change much).
Somebody just got back from one of those cool, all expenses paid, junkets to Seattle! I wonder which superstars of the Windows world he got to eat lunch with at the Redmond campus! MMM mmm good!