I think they should just cancel the show and move forward with a spin-off. If the new voices don't work and the characters don't feel right anymore your basically just tarnishing the brand and then maybe you don't even have a spin-off to go with. You don't want to be one of those shows like "House of Cards" where you try and make it work when you loose maybe the most important person in the show because of his real life bad behavior. I recall people at the time also talking about how loosing Kevin Spacey would be fine. The show would still be fine.