Should have switched to AMD Ryzen.
The whole reason that Apple brought CPU designs in-house was because it will become a competitive advantage over the next few years, much like the PowerPC days. Ryzen is the fastest consumer-facing CPU out at the moment, but Intel could just as easily leapfrog them in the future. Sticking with a third party solution designed for a huge number of OEMs means that Apple will always be limited in how much optimization it can do. As we saw with iOS devices, Apple has been able to squeeze out so much more performance and power efficiency with inferior specs (on paper) when it is able to create its own custom solutions.