using TWD as a measuring stick is misleading. The popularity of the comic/show coincided with a cultural rise of interest in zombies. The book and show are a great product, but I think they caught lighting in a bottle the way that the once-in-a-generation cultural icons do; Star Wars, TMNT, Star Trek are a few. I'm not saying it can't happen again - there are a lot great books out and I'd love to see some of these creator owned books get big. I know other boardies feel the same way.
That being said, NBC programming is currently terrible, so if TSG is done well, it could be a hit for them.