I don't know. We're all used to the idea of Cumberbatch being Khan that I'm fairly sure our reaction to him being a white guy is played out. We've had a year to go through "Cumberbatch isn't Indian." "Neither was Ricardo Montalban." "How dare you go there! Your mother!!" Really, even if the movie did make it clear he was Khan, there'd be some grumblings from the Never Happy Crowd but I don't think it would be far beyond that.