If the show ends, why would Nickelodeon get rid of the property. If the show runs its course, than Nickelodeon can just put it aside for a while and then just revamp it again like they did with this show. That's the thing about Ninja Turtles. It's been able to get consistently rebooted quite successfully over the last 30 years, aside of the live-action series.
Look at what Hasbro does with Transformers. Once one era or initiative runs its course, they end it and then revamp and change it up. With Nickelodeon and Ninja Turtles it will essentially be the same.
"This is true. This is real. This . . . Is . . . STRAIGHT EDGE."