If I'm understanding the stuff on the Palette board correctly, there was to be a battle to determine the leadership of the Gym. However, I have found no mention of the battle actually happening, and I have found what looks like speculation on the outcome.

If Misty wins the battle, it may be that she becomes the sole leader of the Cerulean Gym, which might discourage her from heading out on another journey. If she loses, who knows.