First to the guy wondering if they are 'cutting short to end the WD tv show'.. the answer is, most definitly not. I highly suggest reading the graphic novels which is much different than the TV series but if you did, you would know that characters in the WD die left and right. **kind of a spoiler** Many of the characters you think will live forever will die. This is what makes the GN and TV show so good, is that they do not hold back anything. It is one of the most pseudo-realistic zombie apocalypse stories ever written, in my opinion. Not to mention the ratings for the show are off the charts. So no, I don't think the show is going to be cancelled any time soon. I actually think we will see many more seasons to come.
Just for the record, reading the graphic novels will not ruin the show and watching the show will not ruin the graphic novels. But like most movies/shows, the books are always better. You think the show goes overboard? oh man, you have no idea ;) So if you like the show, you are totally missing out if you haven't check out the GNs.