This is according to developers Steve Troughton-Smith and Johnathan Levin (via 9to5Mac) who have discovered some information within the BridgeOS 2.0 software that hints at that possibility. Assuming the information is correct, the iMac Pro could be packing an A10 Fusion chipset as a co-processor (it’s the same chipset used in the iPhone 7, 7 Plus).
https://twitter.com/stroughtonsmith/status/931994004887044097
Further digging by developer Guilherme Rambo has revealed one potential use of the A10 Fusion, which is to allow the iMac Pro to enable “Hey Siri”, a feature that is missing from the macOS version of the digital assistant. Troughton-Smith adds that the inclusion of the A10 Fusion will allow Apple to have tighter control over macOS without upsetting users and developers.
Confirmed: "Hey, Siri" is coming to the Mac pic.twitter.com/Dw9bRAzbxD
— Guilherme Rambo (@_inside) November 18, 2017
Apple had originally announced the iMac Pro at WWDC earlier this year, but during the announcement there was no mention of the A10 Fusion. We have heard that the computer would support up to 18-cores of Intel’s Xeon processors, but like we said, no mention of the A10. It is possible that the A10 is meant to be a surprise feature, but either way we’ll find out once the iMac Pro is released, which last we heard is scheduled for the end of 2017.