I'm a bit afraid The_Interloper could be right, although Apple rarely cancels major products after they've discussed them publicly - there's a difference between a charging pad and a workstation. If we neither see nor hear of any progress by WWDC, I'll be really afraid that The_Interloper is right.
If Apple were really just offering an iMac Pro in a desktop or tower case, why is that taking so long? I agree that it would be 10-20% faster than the iMac Pro with the same CPU and GPU because of fewer power and cooling restrictions (assuming Apple offers a beefy power supply and excellent cooling, rather than a Mini/Cube/Trashcan type design). They might get another 10-20% on some applications by offering the Radeon VII instead of the Vega Pro 64X as the top GPU. They should have been able to get that machine out within a couple of months of the iMac Pro (minus the top GPU options) - it could literally be the same motherboard.
A two year delay suggests something else - and their comments on performance suggest that it's more than a minor bump by removing power constraints from iMac Pro parts.
Would people be happy or disappointed by a Mac Pro that offered the following?
Here's where it's like an iMac Pro:
The same CPUs and GPUs as an iMac Pro (with a Radeon VII available as a +$300 upgrade from the 64X).
No underclocking - sufficient power and cooling that the CPUs and GPUs perform to spec (but no overclocking).
The same price as an iMac Pro of identical specification (the bigger power supply, different case and an additional Apple Tax to keep margins high with easily expandable RAM and storage make up for the screen).
Here's the expansion:
8 RAM slots, 2 banks of 4, ECC, easily accessible.
2 accessible NVMe SSD slots in addition to a soldered boot SSD.
1 accessible X4 PCIe slot - no GPUs - it's an X4 slot with 75 watts of power.
I proprietary connector for an additional Apple GPU Module (AMD only) - you can also remove and replace the stock Apple GPU Module .
6 TB3 (3 buses)
2 10 GBe
No other ports
By my very rough count of PCIe lanes, it works (if there are dual GPUs, either the chipset adds more lanes than it's connected to or the GPUs are both x8). This is 48 lanes without any used by the chipset (but some of that I/O will come off the chipset, replacing what it takes). It needs about 500 watts for the Xeon W-2195 and a Radeon VII, so 750 should cover the whole system (1050 if dual Radeon VIIs are possible).
More expandable than your basic iMac Pro, no NVidia and feasible. Does it appeal? It seems too similar to the iMac Pro to have taken this long. This doesn't live up to what Apple's been saying, but it's close to what folks here are predicting?
My guess would be something similar to this, but +$1000-$2000, maybe some clever modular design that allows more choices, and with the next step up in CPUs (which also means that there are very high-end CPU options - this only allows iMac Pro CPU performance) - but maybe I'm wrong, and it'll be this similar to an iMac Pro?