Could Fantasy Flight Games' Only War: Enemies of the Imperium cover, designed by Imaginary FS Pte Ltd, well be the same art for the new Ork Codex? It's not out of the realm of possibility.
Fantasy Flight has used GW codex art in several of their RPG supplements so it's possible we could see some of the Only War originals in future codices. The art is eerily similar in style to all of the 6th edition codices thus far.
While I really hope this is the one, we'll just have to wait and see :)
