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.
Cumberbatch has a big following in China, and in Japan (for a Western actor) - without him the take in China would probably have been a fair bit less. Maybe casting known Indian star would have made up for it, maybe not.