>Will Vulkan really replace long-term OpenGL?
I've never tried Vulkan myself but I watch threads regularly @ GameDev.ru and I gained some insight into it.

Vulkan has *extremely* high entrance threshold. Many menial tasks the OGL / DX driver performs "under the hood", tasks you never had idea exist (like syncing memory access between rendering stages), Vulkan requires you to program explicitly. Thus, even to make a rotating cube work you have to have very good in-depth understanding of how videocards work and their components interact.

So, a simple answer, no. It is possible that OGL / DX will be (or already are) rewritten to be wrappers around Vulkan, but it the fact is Vulkan is a tool for seasoned pro veterans. 95% applications out there don't need such level of control over the video card.