It's very possible the T2 chip inside the iMac Pro will be the end of Hackintosh. Surly it will eventually trickle down to the entire Mac line. It checks the boot to be 100% Apple. It can be deactivated, but the default is on.
From what I understand, the boot process starts on the T2 chip. Getting its credentials to approve boot will be difficult, if not impossible.
From Macworld's review by Jason Snell:
"When you start up the iMac Pro, the familiar Apple logo appears almost immediately. This is a sign that the T2 is taking control. For security reasons, the T2 is the iMac Pro hardware’s “root of trust,” and it validates the entire boot process when the power comes on. The T2 starts up, checks things out, loads its bootloader, verifies that it’s legitimate and cryptographically signed by Apple, and then moves on to the next part of the boot process."