Support to modders, more content, maybe cosmetic DLC's like for Killing Floor.
I have nothing against optional DLC for weapons or cosmetic items, badges for your character as long as they don't give an unfair advantage over the other players.
What else? Maybe a KF 2 if TWI has the funds to support such a project, or improve Killing Floor 1, continue to add features to it. RO 2 also needs some more polish, tanks for example need to be better at collisions with objects. BUT the most important is to make them more powerful, when up against uneven terrain or a higher hill, to prevent situations when a tank gets stuck, while in reality it would probably carry on...
There's a lot of perspective, and I think RO 2 is the most detailed WW2 tactical shooter. Best cover mechanics and weapon handling, which is definately an improvement over RO 1 and Battlefield's content, and a rather unfair, in my opinion amount of DLC's just for maps and such.
Long live Red Orchestra!