difuid :
It is more of a proof of concept if anything, USB-C could drive (as in supply power and signals) bigger monitors as well. Only problem is that GPU card and motherboard manufacturers are neglecting the tech as developing the power routing would cut into their bottom line.
I personally would love to use single cable monitors.
That would still be a pipe dream. Taking a random sample of monitors in my office (22" to 24" HP/Dell panels). They're rated for 115v & 1.5A to 2.0A ~= 175w to 230w (this is ignoring the AC -> DC loss which ranges from 10% to 60% but I don't have the data on hand for these monitors so you'll just have to bear with me). The USB PD spec tops out at 100w. An updated spec would be needed as 20v at 5A won't be enough. But, this probably won't be the biggest hurdle...
Video cards will need to deliver enough power to drive 1 panel? 2 panels? 6 panels? That's 175w to 1000w. The control logic is simple, modern video cards contain billions of transistors, it will take a few thousand to get the PD spec functional which is essentially rounding error... But the power problem hasn't been addressed yet. For the video card, that's simple, just add a pass-through and pull the power from the power supply.
So about that power supply... OEMs tend to skimp, your typical Dell/HP/etc desktop comes with a 250w PSU. To support a single monitor, they would have to start including 400-500w PSUs. Your Fancy AMD Eyefinity/NVidia Surround card will need a 1200w PSU to supply all 6 monitors.
All that doesn't take into account the DC 12v to DC 20v step up that's needed. Modern PSUs only have a 12v rail. To make this remotely feasible, ATX spec would have to be augmented to add a 20v rail. This will certainly make Seasonic/HiPro/etc happy...
A few other things to consider: This is only taking into account 24" panels, there's still 27"/30"/32" panels that I don't have power data for. Or what about 75" UHD TVs? USB hubs built into the monitor (do they need to support USB PD too)? Monitor speakers?
TLDR: you're going to make Dell/HP cry