JJ Abrams has went on record to state that William Shatner is not ruled out as a possibility for showing up in the next Star Trek film. Neither he says is Trek fanboy Khan. Although, says Abrams, they may not follow contemporary canonical storylines as Trek fans know them.
This is what he has to say.
"[Khan and Kirk] exist — and while their history may not be exactly as people are familiar with, I would argue that a person's character is what it is," said Abrams, explaining that new-Khan could be as bad as old-Khan despite disimilar backstories. "Certain people are destined to cross paths and come together, and Khan is out there ... even if he doesn't have the same issues."
I don't know about brining Shatner back in, too much pandering to fanboys is not a good idea but forging their own storys and pathways in the Star Trek universe is a much better idea than simply retelling the old ones with a new cast and better 'splosions n stuff.
Abrams has already proved himself a first rate storyteller and director so i have the utmost faith in him leading Star Trek forward again.
Maybe he'll even kick start a new series, i mean the man knows how to put together a tv show.