If I had done it: Harrison is pretty much the same, an augment--but a new generation of augments, the first of several. He escapes, his brothers and sisters are frozen and stuffed in the drone-torps, and he begins to think of himself as the heir to Khan's legacy. His DNA was modeled on Khans and improved beyond Khan's, of course he's superior to Khan, Harrison the turn King where Khan was a mere Prince. How dare Marcus and Starfleet imprison his people; how dare they hold back their rightful leaders. If I had to show Khan, after credits: A shot of a battered and beaten Botany Bay, and inside we see Khan still in cryo sleep. Just leave it there. He's out there, maybe we'll find him, maybe we won't.