This huge delay on Mac updates is making me think that ARM Macs are coming sooner rather than later.
Yes... Perhaps the ARM Mac project used to run as a small "just-in-case" R&D effort. But at this point it's hard to believe Apple isn't shoveling resources into it with an eye to making ARM macs viable ASAP.
The A9X isn't really too far off. Consider that the Mac form-factors alleviate power and heat management constraints that Apple's current processors operate under -- with the more powerful form-factors having the least restrictions. E.g., an ARM iMac would not have battery constraints at all and can comfortably accommodate fans and other bulky heat management techniques. A MBP form-factor needs to run off a battery, but a large and powerful one and can accommodate smaller active heat management components.
I guess that's my long way of saying I don't think Apple is too far off making ARM-based macs as powerful as Intel-based macs across most of the lineup.
The software transition is the big question mark to me... developers will have to recompile and rerelease... this isn't the old days so many will be well positioned to do that with relatively little effort but many also won't. In the end users will have to wait to get some of the software they rely on, or pay for a new release, or find an alternative.
So... will Apple provide an emulation like Rosetta for the transition from PPC to Intel? That's certainly possible, but I wonder if it would really be able to run fast enough to provide a reasonable experience. Do they build support for the intel instruction set into their processors?!? Obviously they could not do this in a way that is anywhere near as sophisticated as actual Intel CPUs and this is an expensive proposition.
Hm... I wonder if they might not do *both* and get close to native speed for Intel binaries on an Apple ARM Mac without essentially including an Intel core. Translating one machine instruction set to another can be fast and result in native execution speed... but only when the target has a precisely equivalent instruction and processing model. Since Apple controls their CPU and seems to have the expertise, they could extend their ARM processor with instructions, modes, registers, etc. to make binary instruction set translation lightweight and run at native speeds (or close enough) for the vast majority of cases. That is, they can employ an emulation layer like Rosetta to support Intel binaries but in the common cases where that would result in an inefficient emulation, they could extend their processor with just enough to make an efficient emulation possible, yet come no where close to including support for the full Intel instruction set.