I could see it being Garth. That would be pretty cool.
And I could see Abrams laughing his ass off that the primary fan theories are not about that character. Alice Eve's hairdo and the hand scene in the Japanese trailer were deliberate misdirection just to make it even funnier.
But after the teaser came out and there's this mention of family, I'm going out on a limb and calling it for Kirk's brother, George Samuel Kirk.
Nah, too hard to explain the accent.
Sooo...Garth or Mitchell, Mitchell or Garth. Getting kinda hard to choose. It would be very easy to just take one name and make him an amalgam of both characters. And Garth sounds a bit more threatening than Gary, I suppose, or at least less suburban.