Garth is out, because the character depicted is not (as far as we know) a shapeshifter.
Mitchel is out because we see the character at one point using a BFG in a fight. Gary, with his powers, would not need a BFG. Also, the Gary story was done in the comics already.
Khan has all the attributes of the character depicted in the trailer.
Super-soldier/physically advanced human? Check.
Vengence-driven for a wrong of some sort? Check.
Cumberbatch in a SF uniform could be a flashback to how he came to be wronged by Starfleet after being found, just as he wore one in the Prime universe after Kirk found him. JJ could get around the fact that Kirk is a new captain by having Khan's discovery and exile/imprisonment be something Pike
did, and now Kirk has to clean up his mess.