Good finds. Which video cards have tb3 ports? I can find usbc ports, but those are lower bandwidth usb 3.1 rather than tb3.
There is about zero intrinsic need for the XDR or any other TBv3 monitor to be feed physically off an add-in video card. There is an order of magnitude more modern laptops that have TBv3 ports than 3rd party volume of upper half range new video cards.
Same is true for Mac Pro ( and rest of the current Mac Line up). A new Mac Pro 2019 with a 580X (with only HDMI edge connectors ) can drive an XDR monitor (or any of these other ones). The notion that these monitors can't be feed buy a large and diverse, multivendor ecosystem is myopic, 'missing the forest for the trees' exercise.
Apple is about 2-3 years ahead of the curve here with the Vega II cards with TB connectors on them. DisplayPort 2.0 uses a variant of the Thunderbolt protocol and specifies the TBv3 physical ports in the standard ( along with an alternative).
"... DP 2.0 leverages the Thunderbolt™ 3 physical interface (PHY) layer while maintaining the flexibility of DP protocol in order to boost the data bandwidth and promote convergence across industry-leading IO standards. ... "
Technically Type-C is already part of the DPv1.3-4 standard (not the only phys port but it is there). So this is a just a direct evolution.
It doesn't mandate that 'regular' TBv3 be present also, but with future PCI-e v5 ( or even v4 ) there will be a decent bandwidth to prune off for x4 PCIe-v3 without a noticeable difference to the GPU even under relatively heavy data transfer loads.
What is more likely to disappear over time are the somewhat standard rouge Type-C ports see now that are slight variance off of USB-IF and DisplayPort standards (for VR headsets). Those are actually more so the proprietary ones.
First generation DP v2.0 GPU cards perhaps not ( about 2 years) perhaps not, but probably coming if USB 4 rollout gets deeper traction over time.
When DP v2.0 goes mainstream then Type-C with display port will be a standard; spinning it as proprietary or defacto proprietary will be long dead. (although I'm sure they'll still be a least a few flogging that dead horse in this forum in the future). That light at the far end of the tunnel is an oncoming train.