If you genuinely admire Doffy's legacy as a villain, you would either hope Im nukes Impel Down in a fit of rage, in which case Doffy manages to slip away, or that Doffy dies in prison.
Because Oda would inevitably fail to deliver the writing you expect to when Doffy gets involved with CG, it's either he becomes another reformed villain with a shallow role, or get the Lucci treatment, no other choice.