I think we should get a halo 4 armour skin from pre-ordering Red vs Blue season 10 
Like what kind of skin? they use solid colours.
Maybe the rooster teeth emblem?
It would be awesome if they put something from Red vs Blue in the game. An easter egg, weapon skin, armor skin, maybe a new gametype like grifball in Halo 3!
Red vs Blue now exists for 10 years, they have to celebrate that somehow, an would there be a better way to do that than giving presents to us? 
I´d have also said Red vs Blue Firefight voices, but since there is no firefight in Halo 4, maybe Spartan Ops or Multyplayer voices if there are some.
I’d love Caboose’s voice for Spartan ops (and multiplayer if they exist)!
Maybe they could integrate the RvB characters into the Multiplayer story somehow? They are receiving advanced training as Spartan IV’s or something… After all, they did make that promo for the release date of Halo 4, and they were clearly Spartan IV’s there.
Elijah wood skin? lol.