Isn't the ARM CPU in the iMac Pro supposed to be akin to the chip running the Touchbar in the newer MBPs?

Using it to run a dedicated device within the chassis is different from using it to run apps (let alone the OS) directly on an ARM CPU as part of some transition. I doubt this is how it'd happen, and think the architecture split would be between Mac product lines rather than combining them in a single machine.

It's hard to see how it'd scale, though. If there's supposedly a renewed push for Mac, and especially Pro Mac, how is ARM supposed to achieve that? Unless Apple have some amazing silicon in the works, where they take ARM to genuine desktop class performance levels when they have TDP to spare, I don't see how Mac's reliance on Intel can be compatible with high end desktop performance in the near to medium future.