I'm not sure modern audiences will accept a story arc that has the characters forever living a more grim life. There has to be IMO at some point hope and a search for the "cure,"
The TV writers have said they have basically no interest in doing a 'cure' storyline, and I don't blame them (I believe Glen Mazzara said he felt it would make Walking Dead too much of a science fiction series when he considers its natural genre to be horror).
'Hope' in the context of this series then is stuff like what the prison was at the start of this season, when Rick built it up as the safe refuge the group desperately needed, a place they could settle down on, grow crops in, and have a life for themselves.
So hope is not finding a way to end zombies, it's finding a way to live in a zombie-infested world and to ensure that there will be another generation of human beings (and as such children like Carl and Judith are part of that hope).
Which I think is far more interesting than finding a cure. I'd love to see how people adapt to this new world and what new traditions spring up, like eventually I think shooting loved ones in the head when they die will become accepted practice, and a ceremony may even come about because of it.
I had a thought last night. I know some people want to know how the outbreak got started. I don't think they'll actually answer it in the main storyline, but if they wanted to reveal it they could do it as the last scene, so the final scene of the last episode is sort of the beginning of the show.