Recent spewage from the gob of Japanese mag Famitsu indicates that Final Fantasy series creator Hironobu Sakaguchi has created a new game company named Mist Walker with which he intends to create "next generation RPGs" for the upcoming console generation, possibly together with developers and individuals such as Yoshitaka Amano. Whether or not this means he's leaving Square Enix is up in the air, but no doubt after being tossed off the FF team for good with no more than an advisory role on Final Fantasy XII, we wouldn't be surprised.
Screw up? He fucking singlehandedly saved Squaresoft from the eternal abyss of mediocrity back in the 80's. After creating that, I think he has the right to mess up at least once.