According to our sources, Apple is pondering about using custom x86 CPUs in its next iMacs and MacBooks, during 2017-2018. Nowadays it's hard to avoid the use of x86 ISA in high end and professional personal computers, but at the same time Intel CPUs are too expensive if we compare these with ARM SoCs.
So, Apple's target is to realize a complete x86 custom SoC family, like Sony and Microsoft did with their consoles. AMD is the perfect partner to do this. During 2016-2017 Zen will be in the stores, and Apple would be happy to use this to create a polyvalent and powerful SoC. On the other hand, AMD is becoming a company specialized in Custom and Semi-Custom chips, and a huge contract with Apple would be great (even if it has low margins) to advertise its own business.