There is not a lot to go on to think this is related to Diablo 3, cows and hell? We all thought the censored word was hell in the pcgamer article and that it meant they went to Blizzard.
Again it's a vague article that can point to a lot of games, or a game we have never heard of before. I think if you going to link things to Diablo 3 there needs to be a more solid rope. Some of these are just strings barely holding on.
everything on this site is vague. we have no evident info yet and that leaves us to speculation. and that is what this site is all about.
anyway, cows and hell is pointing to diablo much more than for example sheep and steel, or cars and streets, but much less than if they said tyrael and tristram..
dunno why, i just think there must be some reason why they chose these two lines as these connotations are not often used metaphores in german language. (correct me if i'm wrong, i'm not a native german speaker)