I think there will be a Borg tribble subplot in Star Trek: Into Darkness. All the signs are there. Let me explain. First off, Borg tribbles are practically canon already, since they appear in Star Trek: Online. So, you can't tell me there's no possibility they'll ever show up on screen. Second, we are dealing with an alternate reality, so everything about the Federation's first contact with the Borg goes right out the window. In this reality, Borg were present on Earth in 2063, and were reactivated in 2153. Now, we also have Nero's Borg-enhanced ship, per the Countdown comics. Given all this unexpected presence of Borg in the Alpha Quadrant well before the Borg Collective tried to establish a presence there, it makes sense that the Collective of the 2250s would want to take a look. Third, there is the strategic value of Borg tribbles. They are known for their voracious appeties and prodigious reproductive abilities. If the Borg find a planet to be overly resistant, they can simply infest it with Borg tribbles and starve out the population to the point where they're simply begging to be assimilated. Fourth, we know that tribbles hate Klingons. The upcoming film also deals with Klingons. So, this is what I'm thinking: the Klingons are currently mortal enemies of the Federation. Benedict Cumberbatch's character worked for Starfleet, until he saw that the Borg were using tribbles to starve out the Klingons, and he wanted to do something about it. Starfleet, seeing an opportunity to rid themselves of a major threat, declined to help and forbade him from intervening. Enraged that the Federation would stand by and watch a Klingonitarian crisis unfold, he detonated the fleet and sought revenge. Maybe he liked Klingons so much he even had a Klingon wife, who is now dead. This would be similar to previous Trek villains whose vengeance is also motivated by being widowers. This would explain his later presence on Kronos in the film, and why Kirk and company have to hunt him down: to stop him from defeating the Borg tribbles and saving the Klingons. Don't ask me where he gets his superhuman abilities. Probably from Borg tech he stole from those tribbles. I mean, it's not like they could fight back, right? They'd just squawk a lot, but less than usual, because they save their real squawking for Klingons. Unless he actually is a Klingon spy, like Arne Darvin. You never know. So, that's my theory.