The real danger isn't a smart AI - the smartest people don't end up being in charge of our societies. The real danger is having enough control to be able to con most of our society, and seeing how much our societies are willing to continue participating in clearly compromised special interest social networks, I don't have a lot of faith. Barely a difference if humanity is replaced or just led to the lowest common denominator of exploitation at that point, and that's where we are heading politically.