After seeing Naveen Andrews as the villain in the Sinbad pilot, I'm thinking he could have been a pretty cool Kahn. He even has a history with Abrams. Same goes for Anil Kapoor, from Slumdog Millionaire, 24, and Mission Impossible: Ghost Protocol.
I wouldn't agree with Anil Kapoor being Khan. I've seen a lot of his Bollywood movies and all three of those motion pictures you've mentioned, and I don't think he'd have the ominous presence of Cumberbatch, IMO.