I've hacked the exe file with a hex editor and can confirm it really works. I now have 21:9 in 2560x1080. BUT (!) the hud has gone to the left side of the screen now. good thing my LG monitor has a crosshair function, so it's not that bad for me.
bit late here( had this since release but 360 controller meh ), but just tried the game again and my X52 pro controls work out of the box, much much better with that as a controller, also got ultra wide working with correct aiming hud, bit of hassle but now this game is how it should have been released.