Don't believe that's true when Valve, Epic, and iD have all seemingly solved the shader compile issues. I mean watch that video, they do talk about it and the challenges with having shaders compiled to be optimized for different hardware and drivers and how the temporarily solved it and may better solve it.
Since the game is going to be on Steam anyway, it appears Valve are looking to build a utility into Steamworks to solve that problem, in addition to the whole can't you just compile shaders for the specific hardware and drivers at runtime of the game?
It's my understanding that using generic reference compiled shaders is what makes for the hit in shader performance, and Vulkan doesn't currently offer something with the SDK to getting optimized compilations done for each spec, right? Just like Flavien said about the shader performance is like if you're running DX shaders in debug mode. DX happens to have the utility to optimize the shaders for various hardware to begin with.
Also isn't that something that driver vendors may also solve, to automatically optimize unoptimized shaders? On top of the other various possibilities. It's not nessisarily a "Khronos Group must fix this or we're screwed" thing.
I figure. I don't believe DX12 is an option, though. Only about about 33% of Steam users are using Windows 10, and the adoption has only increased by 1% per month the past 4 months.
Even if you don't consider screwing over backers in that they must have Windows10 if DX12 is the only option, you're seriously limiting yourself to the market that the game can be sold to. I mean, presumably you're pretty much going to be in the black when it comes to crowdfunding alone, while to actually make good money you need to make the game good and have a lot of new customers buy it. If only Win10 users can buy it, it's about 1/2 or 2/3rds less sales that you're likely to get. That seems like a serious no-brainer.
Also as I figured...
So... I mean doesn't it seem best to switch to Vulkan now, before there is more that needs to be reworked in both the rendering pipeline, shaders, and everything else, as it'll make adding a DX12 option later on easier, especially in the case that there are issues with Vulkan?
I also imagine, that a year from now, someone will have made something to automatically convert Vulkan GLSL to D3D12 HLSL like how there are currently tools to convert back and forth between OpenGL GLSL and D3D9 HLSL, to further make that transition easier.
Ultimately, I think the best advice would be to email Valve about it. They're working pretty closely with Khronos group, and spoke of having something in Steamworks to create and deliver optimized shader compilations.
They can hopefully give you a better picture. Granted, Valvetime, so who knows when they'll have that in Steamworks, but they seem seriously committed to Linux gaming.
As for me personally, I don't want to be forced to use Win10 or newer only to play, especially when it said Win7 was the minimum requirement. So it's Vulkan or DX11. Don't even think about DX12 unless there is a DX11 or Vulkan fallback in the options menu.