Enterprise finds the Botany Bay.
The hibernation mechanism has malfunctioned. Khan is suddenly an old man.
Shatner plays him.
Khan/Shatner gets to fight newKirk. There's an epic battle. Khan/Shatner wins.
See? Its not that hard to get Shat back in the action.
!!!!!!!!!!!!!!
Why does this idea make me all hot and bothered?