Vulkan is just a 3D graphics and compute API, it cannot replace DirectX because it doesn't support most of the things DirectX does. Did you mean to say Direct3

Vulkan is just a 3D graphics and compute API, it cannot replace DirectX because it doesn't support most of the things DirectX does. Did you mean to say Direct3D? That's still leave you with input, sound, maths, and 2D missing.