Hi Chaps Are you thinking of doing away with opengl and directx in favour of Mantle support or is it too late damit.
https://forums.uberent.com/threads/amd-mantle-api-in-pa.51882/#post-794986 Short answer is no. Prepare to be pounced on by at least 3 forum members for not using the search function
Two more facts you might want to know: PA do not use DirectX at all while Coherent UI might want it on Windows, but game itself is is OpenGL-only. AMD will make OpenGL extensions which will expose GPU in Mantie-like manner: http://www.dsogaming.com/news/amd-aims-to-give-opengl-a-big-boost-api-wont-be-the-bottleneck/ So if Uber want to do that they can use this advantage of AMD GPUs without using any special APIs.
It's not something Uber or Coherent Labs can change. It's how Google handle their graphics stack on Windows.