D3d8to9 was a very cool project i remember seing some serious fps gains in some scénarios even +500 on some old 3dmarks benchmarks. D3d9 to 11/12 or even Vulkan would be super cool ! (even if it doesn't make any perfomance gains and/or add some major glitches) Who is up to the task ? D3d8to12 would be cool too btw.