This is not a switch from Intel to ARM for Mac, but a ARM coprocessor in Mac similar to new MacBook Pro that handles the Touchbar and Secure Enclave for TouchID. Apple don't even like the idea of touch interface for Mac apps, so its unlikely they will open up running of iOS apps on the Mac.

Curious to see if new Mac from now onwards will still support TouchID as Apple has said that they are abandoning Touch ID on the iPhone. Makes no sense to support TouchID on just one platform, the minor one.