Bringing Arm chips to a Mac could bring efficiency and battery life improvements without sacrificing speed, with Apple also perhaps able to cut down on the size of some of the internal components, thus perhaps allowing for slimmer devices.

An Arm-based MacBook might not need a fan, for example, much like an *iPad*. Apple's iPads also have superior battery life, another feature that could be brought to the Mac lineup.
https://www.macrumors.com/guide/arm-macs/