NCIS. All three.
Not only that but the show lasted more seasons after that episode than had aired prior to that episode. This episode aired in the 5th season and the show lasted 11 seasons. (Six more seasons for people bad at math)
Plus when word got out that Gunsmoke was being cancelled there was a huge public outcry, so massive that CBS changed their mind.In addition to Gunsmoke which James Arness used his influence to keep on the air for way too long, Bonanza tried to go on after the loss of Dan Blocker as Hoss and sort of faded away.