xHDx :
It's all nice and all but there is still uncertainty.
Firstly, Vulkan is probably at least 40%+ Mantle. If you followed Mantle, then you know this is the truth. There are many articles online explaining the story.
Secondly, there is the problem of this not taking off. Maybe it does offer more than what DirectX does or OpenGL, but I doubt many will adopt it. Mantle didn't take off, so I can't see this being getting much further. Maybe im wrong. I hope not, but who knows.
Mantle didn't 'take off' because nVidia refused to support it, and because AMD kept it for themselves since it was still in beta. They were trying to figure out whether to make it open as is, or doing something else to increase adoption. Rather than opening it up, they gave Mantle to Khronos instead, since they knew it would not get support if nVidia refused to adopt it.
Vulkan will very likely be successful. Since it's on a lot of different platforms, it will make porting easier for developers.There's little reason not to adopt it. Aside from that, it works even on Windows XP. Lots of people are refusing to upgrade from Windows 7 to Windows 10. DX12 is limited to W10, while vulkan works across pretty much all windows platforms... That alone increases the potential buyers for developers over DX12, so... It should do fine.