I was just reading another topic and thought to myself, why haven't Ash and May won a Tournament/Grand Festival? They will have their goals complete once they do, so they won't leave until they do! It's really just a theory of mine, but I bet they won't leave as main characters until their goals are fulfilled. Misty wants to be the world's best Water Trainer and she's attempting that while fulfilling her other goals, to be as good as her sisters, no better and to be the Cerulean Gym Leader. Tracey is fulfilling his dream while helping his idol, Professor Oak, of being a great Pokemon Artist. Brock wants to be one of the best Breeders in the world and he travels with Ash and his friends learning more as he goes, only taking time off to help back home at the Pewter Gym and to serve the woman he loves (When he stayed with Prof. Ivy). Gary wanted to be the best, but changed that and has only seen in an episode of Pokemon Chronicles. Max wants all the knowledge and to be a great scientist like his idol Porf. Oak. May dreams of winning a Grand Fesitval and won't quit, or leave, until she does. Ash wants to be a Pokemon Master, so even after eventually winning a Tournament, he may remain to work on his skills and work his way to Pokemon Master.