I don't think that's necessarily the case - I think that if Apple switched architectures now, there would be a lot fewer issues than there were with the Intel s

I don't think that's necessarily the case - I think that if Apple switched architectures now, there would be a lot fewer issues than there were with the Intel switch. Over the past few years, Apple's done a lot of work in making the same system APIs available across multiple processor architectures; at a base level, iOS and OS X have very similar cores. You can see this with the ease of the transition from ARMv7 to ARMv8, which in most cases just required a new compilation. As general-purpose applications have been migrated to higher-level APIs, the difficulty of porting those applications to a new processor architecture decreases; if an application is Cocoa-based and compiled for x64, then if those Cocoa APIs are available on an ARMv8 platform, they can be compiled natively for that platform.