Well just noticed that AOTS was included in the latest humble bundle monthly so wanted to see if it was supporting Vulkan yet (not super interested in RTS myself) and looks like support will be coming shortly:
https://forums.ashesofthesingularity.com/483199
AFAIK this will be the first game to offer DX11, DX12 and Vulkan all in a single game engine.
## Vulkan ##
We were hoping to get Vulkan support included with the June patch for episode 3, but unfortunately it's being delayed to a later date. Draginol: "The NVIDIA dev team has been at the office all week helping us optimize Vulkan support for Ashes. We'll likely have to time our release on the Vulkan version with when NVIDIA and AMD have their driver updates that support the parts of Vulkan we're using."
https://forums.ashesofthesingularity.com/483199
AFAIK this will be the first game to offer DX11, DX12 and Vulkan all in a single game engine.