It won't, unless only a fairly small elite ends up using Vulkan. And I believe that's what will happen indeed: Vulkan is low level enough that most likely, only engine devs and middleware devs will touch it.

You will of course have the occasional cowboy (which I personally am, though in a different domain), but that shouldn't matter that much in the grand scheme of things.

Now if you ask me, Vulkan is not enough. What we really want is a stable, usable hardware interface. Basically an ISA. The thing will have close to zero bug, because hardware folks know how to properly test their designs. Undefined behaviour is likely unavoidable, but I believe it can be reduced to a reasonable minimum.

If AMD and NVidia started something like RISC-V, except for graphics cards, it will likely have a greater impact than RISC-V itself.