Just a thought....any chance that the villain in the next Trek movie is Jim Kirk's older brother?? I know, I know....it was just a thought but highly unlikely.
Unless he's on PCP or something to explain how...
...I'm not so sure it can be Sam.
I have a wild guess, what if it was that creature from the Next Generation Episode "The Skin of Evil" you know the one that killed Tasha Yar? It has been around for a long time, so it is probably still on that planet in the 23rd century, its goal is to get off that planet and get revenge against its masters for leaving it behind, and it looks like a dark oil slick. Now what if a change in the timeline caused it to be discovered a bit earlier and it gets off its planet. I mean the name of the film is Star Trek: Darkness, maybe this is the "darkness" to which the movie title refers.