I was just pointing out specifically that there is no such thing as PCIe-based video - nor is there any need for that.
Support for USB4/Thunderbolt DP will proliferate, but there is still benefit to a DP altmode as it's free to implement (the host controller just wires its existing DP input lanes directly to the USB-C connector) and allows for super cheap passive adapters.
If USB-C ends up becoming the standard video connector as well, it will most likely be DP altmode as you then only need a cheap USB-C controller to negotiate the mode.
There isn't really any pressure to invent a new protocol. https://xkcd.com/927/