I don't know if I'd like a comeback. What made all these shows special was that they were short runners that left us wanting more. I mean, compare that with The Simpsons or Family Guy that went way over their prime and are shells of their former selves. I just don't see a comeback being just as good as the original. And even if it is, some guy on the internet will pick it apart and ruin it for everyone else, like every single one of these comebacks ever.
I'd love to see a miniseries or TV special or movie or something. Dunno about Pinky and the Brain. I LOVE them desperately, but I think they've done all they could to try to take over the world now.
Though, to be fair, TMNT is a comic book. Comic Book heroes always come back in some form. Look at how many Batman cartoons we've had since Batman TAS, with one more on the way. And every time they interpreted it differently. Comic Book heroes can get away with that. You try to interpret cartoon characters a different way, you get New George of the Jungle. Blech.