Why would they do this? They'd need a new line of ARM variant CPUs to meet the various performance points of the different macbooks and imacs. And they'd be amo

Why would they do this? They'd need a new line of ARM variant CPUs to meet the various performance points of the different macbooks and imacs. And they'd be amortizing those costs over a rather small (for them) number of units. And that would do very little to address the costs of maintaining the OSX software stack, very little of which is CPU specific. Most of those costs are in maintaining a rather different model of UI interaction, software installation, and backwards compatibility. My guess is that they have developed this capability in-house as a form of insurance, and will keep it around and alive as a way of keeping their Intel costs reasonable.