The Khronos Group announced the possiblity of building a new, more "portable" graphics API that would work on top of Vulkan, Metal, and DirectX 12. However, the new portable API likely wouldn't come without some major caveats.
Khronos To Create Meta-API For Vulkan, Metal, And DirectX 12 : Read more
Khronos To Create Meta-API For Vulkan, Metal, And DirectX 12 : Read more