There have been rumors in the past that Apple could be shifting their focus away from Intel processors to ARM processors, and while that has never been confirmed (nor denied), the closest thing we have to some form of evidence would be a recently published academic paper by a former Apple intern, Tristan Schaap, who basically revealed that during his internship he worked on a project that attempted to bring Mac OS X Snow Leopard over onto ARM devices. With his paper titled “ARMing the Snow Leopard”, it seems that he was successful in getting OS X booting to a multi-user prompt using a Marvell ARM processor, but that was as far as he got. In order to get OS X up and running properly, it was said that quite a number of things had to be done. For starters the L2 cache needed to be tweaked, apps had to be ported and new drivers had to be written, all of which definitely could not see completion during his 12 week stint as an intern at Apple.
However given that Tristan now works for Apple as a CoreOS Engineer, if Apple was truly serious about porting OS X over onto ARM devices, he’d have plenty of time to do so from then until now. While this does not confirm Apple’s plans to switch over to ARM, it at the very least tells us that the Cupertino company was once (or still is) interested in moving to ARM for future Mac products.