The Walking Dead - Q&A with Robert Kirkman

How does it affect you as a writer knowing you have 13 episodes this season versus six last year?
It is no problem at all to me, just because coming from comics I'm used to producing—for The Walking Dead I produce 12 comics a year and then I do three or four other comics on top of that. I guess it's somewhat daunting but I'm not even writing this stuff by myself. So it seems like it's a little bit easier.

Do you have an end game in mind for the show?
Yeah, it's something we've discussed briefly. I would like to do the comic book for 15 more years or so—in comic books that's completely normal, not completely unheard of, but it's kind of unheard of for a show like this to go so much as 10 years. So there's definitely going to have to be an end to this but while we have discussed it here and there briefly, we haven't really nailed down an exact end date just yet. We're going into our second season now, so I think it's normal just to look ahead and be a little optimistic and see where things are going to take us.

Source: Full interview (including spoilers) @ E!Online