I've put this theory out before, but what a wonderful way to introduce the Klingons into Nu Trek and play off the TOS concept of Klingons looking human, or possibly surgically altered, or virus altered as in Enterprise. No matter how they do it, Kang looking human (and a iconic canonical character) is not out of the realm of the rebooted mish-mash of old and new that is Abrams's Trek. It makes a little sense, his apparent strength, agility, the fighting style, the anger, and the revenge... it's all very "Klingy". I could see Kang being a rogue, or part of a Kilingon terrorist cell or faction, angry at the Federation and it's freedoms and decadence (*coff* Al Qaeda *coff*). Perhaps he's even a sleeper agent made to look human. A devastated Starfleet and blown up Vulcan, thanks all to Nero, could leave an opening for a highly planned Klingon raid on the Federation and Kang leads the charge. Perhaps Nero was even part of that plan, in deleted scenes Nero is captured by and in a Klingon prison, so maybe instead, the Klingons harbored the criminal Nero, protected him, then let him have his revenge on Vulcan and Starfleet to set it all into motion. PS, I remember rumblings that Abrams wanted Liam Neeson to play Kang in the Trek sequel a few years back... PLUS, the apparent almost casting of Benicio Del Toro, that dude is very Klingon-esque...hmm? Anyway, It's just playful speculation, nothing more... crazy thought?