Board Thread:Speculation House/@comment-29295148-20160825214302/@comment-25936766-20160827125227

73.Anon.52 wrote: ...it may also indicate either Gray was feeling too busy or cast for a new character. I doubt either of these was a reason. If an actor is too busy his character gets less screen-time or is even left out for a number of episodes, not killed outright.

And being cast for a new character is no reason to kill the original. Many voice actors have voiced multiple characters in the same work.