BTW, IF Paramount HAD cast a Bollywood leader as Khan we'd be tearing up the Subcontinent right now.
Don't get me wrong, I love Cumberbatch, but there's an opportunity cost in the Asian market that was missed.
Having finally seen the movie, I have to say that while Cumberbatch was okay, he didn't make a mark on me, and he didn't really seem like Khan at all. Just a villain they decided to name Khan. And he didn't seem all that threatening, really. They waited too long before they made him all eeeevil instead of ambiguous sorta-convenient ally, so by the time he was full evil, the stakes weren't so high IMO. It was a dramatic misfire, and the ending just sort of....happens.
Overall however I really enjoyed the film. Do I still think they should've cast an Indian actor? After seeing it, YES. Time after time during it I said to myself, "Arjun Rampal or Sunil Shetty would've KILLED in this role." It was a missed opportunity. But the problems regarding Khan in this movie are mostly script-related.
Back on topic, would the movie have more appeal in India if Khan was played by an actor that traditionally chews scenery as the big-bad? Maybe. But the international take of Into Darkness is pretty darn healthy.