The Khronos Developer Blog announces that multi-GPU support in their Vulkan API is not tied to Windows 10 (thanks DSOGaming). They say this will come to "many versions of Windows, including 7 and 8.x. Here's word:

One key question that we have been asked since GDC is whether the Vulkan multi-GPU functionality is specifically tied to ship only on Windows 10.

The good news is that the Vulkan multi-GPU specification is very definitely NOT tied to Windows 10. It is possible to implement the Vulkan multi-GPU extension on any desktop OS including Windows 7, 8.X and 10 and Linux.

Some of the Khronos GDC presentations mentioned that for Vulkan multi-GPU functionality, Windows Display Driver Model (WDDM) must be in Linked Display Adapter (LDA) mode. That was not a very clear statement that has caused some confusion. And so it is worth clarifying that:

1. The use of WDDM is referring to the use of Vulkan multi-GPU functionality on Windows. On other OS, WDDM is not necessary to implement the Vulkan multi-GPU extension.
2. On Windows, the use of LDA mode can make implementing Vulkan multi-GPU functionality easier, and will probably be used by most implementations, but it is not strictly necessary.
3. If an implementation on Windows does decide to use LDA mode, it is NOT tied to Windows 10. LDA mode has been available on many versions of Windows, including Windows 7 and 8.X.

Khronos always strives to make its specifications as cross platform as possible. Of course, what products ship on which OS is up to the implementers of each specification, but Khronos is already aware of vendor plans to ship multi-GPU functionality on platforms other than Windows 10, including Linux.