And THAT is what Nick fears. they dont want people to think, "if aang, katara, sokka, momo, appa, zuko, etc are not in the avatar series after aang, then im not watching the show." And so many people watch Avatar. Nick draws people's attention with Avatar, and use it to broadcast upcoming events on Nick, making fans of avatar be like "im gonna watch that." the truth of advertising...and anyway, when a new episode of spongebob comes out, people say, "eh! i'll just tape it and watch it later." But it's different for Avatar. No one tapes Avatar, everyone watches all of the episodes of it, because avatar just does that to people.
Anyway, spongebob will live on in long-waiting episode premieres, more seasons, and lastly, if all else fails, a spinoff. The question is, what happens to nick after that? Avatar will be ending on Saturday (and Avatar is one of nick's top-rated shows). After Spongebob ends, there is still Fairly Odd Parents. Ratings for that are top high, with the arrival of Poof and all. It was nick that even got the FOP members to create more eps, but even that is going to slim down soon. You can only do so much before BANG, everything falls. Disney Channel, Nick's rival, however, has Wizards of Waverly Place, Hannah Montana (which has stopped shooting), Cory in the House, and Life with Derek. Excluding Hannah Montana, all of the series are new. Nick only has Avatar, FOP, Spongebob Squarepants, The Mighty B, and most-likely ending Avatar. Nick is desperate for new shows and such. If the desperation got bad...Avatar would be renewed and Spongebob would get a spinoff, while the Mighty B would be kept alive. And then...Nick would have to find a new series to pick up (I heard Hank Zipzer series is requesting a show. Nick might pick that up).
Now, do you see it?