Vulkan is much more detailed and lowlevel than opengl.
You mean id tech6 would be better, more performant, more beautiful it it were rendered in d3d?
d3d is another api to learn for a restricted platform, whereas opengl can applied to all platforms, as a subset also on mobile. D3d really must be better about some larger factor to be a feasible choice today. It doesn't seem to be so (see this doom engine for example).
Vulkan is not available on PS4 and XboxOne which are the main targets for game development like it or not. This almost immediately rules out implementing a Vulkan graphics back-end because when you support XboxOne you are already using a version of Direct3D-12 so why bother with Vulkan if you can modify your existing XboxOne Direct3D-12 implementation for PC with a lot less effort. On top of that, support from both Microsoft and GPU vendors will be better for Direct3D-12 than it will be for Vulkan. Linux sales are so small it's not worth implementing another graphics back-end for.
That's how it is and will be as long as Microsoft shares their Direct3D implementation between their platforms (Xbox and PC).
There will always be exceptions but they are exceedingly rare and will continue to be so for the foreseeable future. Vulkan has a future but I expect it to be more of a mobile focused one.
