Apple recently hired Mike Filippo, who formerly served as ARM's lead CPU architect. While this move may mean that Apple will begin developing an ARM-based MacBook (as so many have hoped the past few years), it is more likely that Filippo will fill the role of Gerard Williams III, Apple's former lead mobile CPU architect who left the company earlier this year.
https://www.notebookcheck.net/ARM-s-lead-CPU-architect-Mike-Filippo-hired-by-Apple.426484.0.html