There's no end in sight for The Walking Dead on AMC, and the network has said that they want to try to turn it into a Star Trek-style franchise that has insane longevity. But let's pretend for a second that the show's ratings take a massive dive, and for whatever reason the writers just start pumping out crap season after crap season and the fans completely turn on the show and openly reject it. If that happened, AMC would probably bring the show to an end, and if that goes down, creator Robert Kirkman wants fans to know that the end of the show wouldn't spoil the ending of the comic book because they're going to end in two different ways.
Kirkman appeared on an episode of Kevin Smith's Geeking Out and explained his methodology:
George R.R. Martin collaborated with the Game of Thrones showrunners a while back by giving them a roadmap of how he plans on ending his novel series, so we can expect there to be some crossover when that show ends. But it sounds like Kirkman is making sure fans of The Walking Dead comics and TV series will have two distinctly separate experiences when it comes to those endings.
I like that two-pronged approach, and I sort of hope that Martin is being sneaky and keeping the "real" ending of his A Song of Ice and Fire for himself and his longtime readers. There's just something that feels wrong about a show based on a book (or comic) to come along, get popular, and then beat the books or comics to the punch with the ending and take all the glory.