I was just reading the Orruk Warclans battletome and came across this passage. I'm not sure if anyone has pointed this out yet.
"Orruks are incredibly difficult to eradicate from an area once they infest it, especially if that area has lots of caves, fissures and dark places where they could spawn young. The scholars of Hysh believe that when an orruk is slain and its corpse left to rot in the right conditions, it will deliquesce into a fungal jelly. It then puts down thin, whitish strands into the earth below that can harness nutrients and the inherent magical power of the realm itself. From this greenish flesh sac comes the young of the race, glistening and pallid, gnawing their way free from the meaty jelly of their progenitor. These gangly, fang-mawed horrors will slither into somewhere dark and wet, red eyes glinting in the gloom as they take shelter in a fissure or crevice."
Something to think about at least, with all the speculation about the "new breed". Although the inherit sneakiness the trailer insinuates isn't very orruk like.
Could also tie into the "hobgoblin" type that has been rumored that's not a goblin but not quite an orruk?