HwGeek

TB3 on AMD platform? Finally!
So what do you think will stop Apple from dual sourcing CPU's from AMD also?

ASRock is ready with its own mini-ITX motherboard based on the AMD X570 chipset, the X570 Phantom Gaming-ITX TB3. This tiny powerhouse one-ups other mini-ITX motherboards in its category by offering 40 Gbps Thunderbolt 3 connectivity over USB type-C, in addition to USB 3.2. This Thunderbolt port also includes a DP pass-through from your discrete graphics card.
https://www.techpowerup.com/256005/asrock-unveils-x570-phantom-gaming-itx-tb3-motherboard

Why apple not buying custom x86 APU's/Threadripper style? AMD can make it for them and it will be Apple exclusive -like AMD does for MS and Sony.
Apple will save massive amount of $$$ if they drop Intel and all the problems with it ?(i9 TDP?).
This kind of problem were the reason to drop nVidia -right? With this "40%" performance hit, customers will blame Apple while it's only Intel's fault.

Mark my words, New Mac Pro will be AMD based + Intel TB3 standalone expansion card.
Intel has no CPU to add value to current iMac Pro 18C, and also no solution will be upgrade(future Intel's CPU's will require new socket).
I think it will be semi-custom models for APPLE needs (Something Between EPYC ROME ~ThreadRipper3) with 8ch memory support.
Also with blazing fast NVMe storage thanks to high count AMD's  Gen4 PCI-E lanes. and it's gonna be sold at nice premium price.
Also Vega VII 16GB and 32GB models.
P.S - as Welshdog said:

Mostly because really powerful PCs were available with lots of slots and fast CPU/GPUs - much faster than any available Mac.

New ThreadRipper with 48C~64C is coming this year(+ Gen4 PCIE), and no one will spend High premium $$$ for slower Intel based Mac Pro this year.

P.S:
TB on ThreadRipper platform:
"Here we show off the Gigabyte Designare X399 w/the Gigabyte Alpine Ridge TB controller. "
https://level1techs.com/video/where-thunderbolt-threadripper-here-it

Mike Wuerthele said:

I'd be completely on board with that, but I suspect a shift to an AMD CPU isn't going to happen. 

If not, what APPLE could use for their Mac Pro? until Q2 2020 Intel won't gonna have real 10nm competitor even for their current  Top Xeon lineup (current 14nm+++ much better the first/2nd  iteration 10nm parts).
Sry for going OT.

P.S, it's interesting why NV CEO could not convince APPLE to use their products, there must be a better reason why APPLE chose to prevent their Mac users to use any Quadro/TITAN/RTX cards rather then just a bad blood between them.

Hi all, I'm new here :-),
I must say that IMO, this year APPLE gonna release the new MAC PRO with AMD's 7nm "ThreadRipper" variant, but custom made for APPLE specs (8CH Memory/different clocks?) and also 16GB/32GB Radeon 7.
APPLE waited enough for Intel, and finally with up-to 64C/128T 7nm ROME CPU there is massive performance improvement that will justifying releasing ALL NEW MAC PRO.
On mobile side, APPLE will start moving to it's own in-house developed CPU/GPU.

I am sure APPLE monitor's how many Hackintosh PC are built since there is no new MAC PRO, and APPLE can make really nice profits on 32C/48C/64C MAC PRO's with VEGA VII 16GB/32GB.
This new 64C/128T ROME based Mac pro could deliver up-to 4 times the processing power om top spec'ed iMac Rpo 18C!.

Since Nvidia support was abandoned in macOS Mojave, it's just clarifies it.