[kbenson]

Oh, I'm fairly sure they've tested all their MacOS core software that comes with the OS (and the OS), but all the third party stuff and things in the MacOS app store likely need a lot more time. (at least for those that weren't already shipping iPhone/iPad versions).

[duskwuff]

My expectation is that any ARM laptop/desktop made by Apple would include some form of x86 emulation, just like they used during their PPC-x86 and 68k-PPC transitions.