User blog comment:Xilinoc/Ch. 545 - Blue Stripes/@comment-5657895-20130709152835/@comment-11051098-20130709154604

He did age just after the 3 month Dangai training. But if he became a captain, he would probably be a better/stronger one in a normal lifespan of maybe 60 years more, than some other captains.

Unless Urahara or Mayuri invented something that could slow his aging down. He is a soul after all, in his Shinigami form, and if his aging were to be slowed down to the rate of a normal Shinigami, and he could life for centuries if he didn't get killed, he would definitely be one of the strongest captains ever.

But I don't see him suited for such a position. I don't even see him accept it in the first place. I doubt he'd be willing to leave his family and friends, unless it's only meant to be for the time the war lasts.