As we have disclosed some week ago, Firaxis Games team will use the main DirectX 12 features (asynchronous compute and explicit multi-adapter) in order to improve Civilization gaming experience.
Finally AMD and Firaxis Games has confirmed our statement: “Today AMD, 2K and Firaxis Games announced a technical partnership to implement a truly exceptional DirectX 12 renderer for Radeon GPUs into the graphics engine powering Sid Meier's Civilization®VI”.
This means that probably AMD GPUs will have a huge performance boost, just as we have seen with Doom thanks to Vulkan API.
It appears that Firaxis Games has chosen the DirectX 12 API because it has a better System Memory Management/Allocation and a better debugging tool than Vulkan API, at the present moment.