Apple didn't move off Samsung entirely until the A8, and they still rely on many Samsung hardware IPs within the SoC to this day. It was not just a fab arrangement from day 1. https://twitter.com/calebccff/status/1472517091970494465
Apple relied on many of the same suppliers as the rest of the industry for a very long time, except the ones they acquired and closed-off. Purely on a "rising tide lifts all boats basis", Intel would still have had access to the dominant player if the ARM-based touchscreen era wiped out the incumbents. However, this is still a very low-margin business, despite requiring more engineering effort than desktop.
You could argue that $1500 phones were unthinkable at the time, but as a commodity, chipset manufacturers see less than 5-10% percent of that, even on flagship phones.