Ask yourself this. Do you think it wise to cut a source of constant advertising for your product? Would you benefit from losing revenue from DVD sales of Seasons as well as Movie sales? And finally are you okay with losing profit from all anime related merchandise?
Aside from the monetary standpoint, why end something now when the character has yet to accomplish anything of note or make much progression throughout the years? Instead keep the character and progress him work him into the trainer he needs to be. Ash and Pikachu are faces of the franchise, getting rid of them is pretty slim.