I can see it going either way, Master Chief (Who I would be cool with by the way) is definitely a possibility with Microsoft already on board regarding Smash, It's really hard to believe the face/mascot of their Xbox brand didn't come up as a possibility during negotiations and it kind of feels like everything was set up for Master Chief and feels like a matter of not if, But really when.
Crash Bandicoot definitely has everything going for him and then some, But with Activision yet to be involved with Smash, But has worked with Nintendo before in the past with other projects and regularly supports their consoles, It's really all a matter of have they been approached by Nintendo and able to strike a deal.