If Microsoft is launching Windows 10 (a full desktop version, not RT) on ARM processor, you can bet Apple is working hard on getting OSX (full desktop version, not a crippled iOS) to run on it's ARM A11 processor too...
Apple needs to do this, because the laptop/tablet/phone will eventually be just 1 mobile computing device......And if apple is going to be spending time to get OSX (full) to run on ARM, you can beat there's no need to keep x86 around for the desktop....And apple is experienced and good at switching processor technology..It did this when it abandoned the PowerPC processors for x86..... And it really doesn't make sense for Apple to continue to build it's on ARM processor in house for mobile and source x86 for desktop.