"Never say never," but let's be honest: There are certainly episodes from the show's history that will more than likely never be officially shown again. Among those:
Episodes with furs, stuffed or mounted animals or animal rugs. Even with Bob's passing I'm sure out of respect for his memory his estate will not allow fur episodes to be shown.
Earliest playings of Cliff Hangers using "Whistle While You Work", unless the producers want to pay Disney a licensing fee.
Playings of Shower Game because of the controversial reason of its retirement.
Playings of Finish Line because of Bob's dislike of horse racing.
Playings of Bump because of its provocative nature, although one episode slipped by, and we're not sure if this official yet.
Any thoughts of any individual episodes I might have left off?