> If apple uses its own chips, I would assume that they would be aarch64 and not x86_64. Also, Microsoft has some magics for executing x86_64 binaries on aarch64 with good performance, so Apple may have a similar technology.
They definitely do have OSX running on ARM64, they had OSX running on x86 for years before the switch (in fact they had OSX running on x86 before it even was OSX, NeXT ran on x86, SPARC, PA-RISC and 68k, PPC is the one Apple had to add), they've already gone through two architectural migrations (68k -> PPC and PPC -> x86) and by all accounts the iOS core is very much shared with OSX, it wouldn't make sense not to port OSX along the way.
> they had OSX running on x86 for years before the switch (in fact they had OSX running on x86 before it even was OSX
Although NeXTStep ran on x86, the MacOS build on x86 was John Scheinberg's personal skunkworks project until it became Marklar in 2001 (and then kept under the hood for another four years). Mind, Darwin was always written to be portable, but it wasn't a deliberate strategy to take it to Intel. This time around though, I too reckon that they have already a MacBook running on an A10X in the labs.
What I'm really curious about is what they've still maintained: what they publicly ship now is all little-endian; are they still maintaining any big-endian port? Do they have a big-endian ARM port? Have they preserved the big-endian PPC port?
They definitely do have OSX running on ARM64, they had OSX running on x86 for years before the switch (in fact they had OSX running on x86 before it even was OSX, NeXT ran on x86, SPARC, PA-RISC and 68k, PPC is the one Apple had to add), they've already gone through two architectural migrations (68k -> PPC and PPC -> x86) and by all accounts the iOS core is very much shared with OSX, it wouldn't make sense not to port OSX along the way.