David Archuleta is the only one who needs to win the competition.
David Cook has, I believe, now established himself well enough that he will have at least a moderate success regardless of his AI finish position. Syesha, who is more of an actress who can sing than a singer, will likely find a home on Broadway or in Hollywood doing musicals.
But "Monchichi"? His entire "selling point" is that he's supposedly this adorable kid that the teen and "tween" girls simply love to pieces. It certainly isn't for his stage performance or his technical skills. But if he does not win the AI competition, that blows a hole in the mystique which I doubt he'll recover from.