Empire Phoenix said something in my “Vulkan thread” too. Bad feelings about Vulkan/Mantle/Metal/DirectX12 - #6 by Ogli
It’s really interesting and yes, Vulkan is meant as a successor to OpenGL which will totally replace that, but the GLSL (high level shading language from OpenGL) will stay for a while even after Vulkan has become the new Standard.
You can compare Vulkan to Mantle and to DirectX12 and to Metal - but Mantle was a one-year-fly that had been dropped by AMD before even reaching a standard status. Metal might have chances just like DirectX12 has chances, but Vulkan aims to become the only cross-platform next-gen 3D API (Metal is for iOS / OSX and DirectX12 is for Windows, XBox, Surface, Windows Phones).
And for the minor inaccuracies in my history etc. post - I wrote that all from my memory. So yes, it’s clear that there might be some minor glitches in that text.