They already ship ARM co-processors in Macs: the T2 chip. An alternative possibility to my earlier musings is that the T2 chip gets expanded to take over more

They already ship ARM co-processors in Macs: the T2 chip. An alternative possibility to my earlier musings is that the T2 chip gets expanded to take over more system functionality—perhaps to the point where the Intel chip looks more like an accelerator add-on card than the primary CPU.