Idris would make a good Bond, but he would have worked better 5 years or so ago. I think he's generally considered too "old" to take a position like that on a franchise movie. He's hitting the age where actors have stopped playing Bond, so they'd get him for a film, maybe two, but then they'd be recasting once again. They need to get an actor who can be there for that 5-10 year process of making a handful of films.