Then the next question: is the target audience really there?
The people who need 18 cores + a pro graphics card are the people who used to have mac pros (or still use them). These people care about expandable and replacable things, and most of all they want to use a screen with several computers because these pro screens cost a ton (Often more than the machine if you want a screen for e.g. video color grading or really serious photo work).
If the screen on this thing isn't up for the task ,then it's an expensive useless addition. If it is that good, then it's a waste to throw it out in 2 years when you replace the machine.
I mean I'm not saying this thing won't sell like hotcakes because it's an impressive machine and a not-very-price-sensitive customer group. But it just feels like they could have stuck these bits into the last mac pro tower, painted it black and had this product out sooner and cheaper than this?