[pannoni1]

Since most syndicated cartoons at the time (and many still do) had 65-episode syndication packages, the final three episodes of Season 3 were written in mind in case no network would pick it up. Seasons 4, 5, and 6 (though summer reruns is mentioned at the end of the final episode that season) did not have a distincitive finale since on a network like CBS, high ratings would almost assure another season. Unlike syndication, network cartoons generally last as long as the network sees that the ratings are benefiting the network. During Seasons 4 and 5, TMNT was the number-one rated Saturday Morning show, so it made absolutely no sense why TMNT would end as long as the writers still had more good scripts. By Season 7, the show still had decent ratings, but low enough to cast a slight shadow of doubt; thus Shredder Triumphant was writted in case CBS dropped the show at that point. Shredder Triumphant doesn't quite seem as proper as the others that Icebot suggested, since Shredder, Krang, Bebop & Rocksteady are still alive on earth, which means they could access some lethal equipment (and how does being homeless affect a villain, given how easily they can kidnap others?); plus the music heard as the show fades to the credits sounds like something you'd hear at the end of Act 1 or 2 with a hint of darkness to the music, suggesting that more trouble lies ahead.

As for The Next Mutation, only after East vs. West, part 5 you can have a definitive ending given that's Shredder's final appearance; you can clearly tell that the writers were going to have a second season had FOX not canceled it.