So back in 2005 or so, Steve Jobs was reportedly really pissed off about the heat/power consumption of the G5 processors. Like, to the point of switching the Mac over to Intel. (Issacson's biography mentioned this in the chapter "We were eyeball to eyeball.")
Supposedly there was a secret group in Apple that works of porting Mac OS X to various architectures in case IBM/Motorola/Freescale don't play ball with them.
What would have happened if Apple HAD switched to Intel after the G5 debacle?