They introduced ARM to manage their fingerprint sensor and the TouchBar. Rumors had it that Apple is working on connecting the ARM chip to more subsystems so it can do background work like background refresh (or what that feature is called when the laptop is in sleep – PowerNap?). I see this as Apple slowly creating a hybrid (low energy ARM for easy tasks and faster x86 for speed). Maybe the goal is a complete transition to ARM and Apple starts to design their own MacBook (Pro) CPUs to gain more control (be less dependent on Intel’s varying release cycles).