I wonder if they'll have Rick descend on TV the way he has in the comic though. He gets pretty dark and amoral, for the "hero" of the series.
I like Rick as the "sheriff" type morally upright character. Since they've kept Shane in the story, they can offload the dark stuff onto him. Shane should be the guy who yells at Rick that they need to do something nasty to survive, and then is the guy to do it, behind Rick's back if necessary.
This allows Rick to keep his leadership standing and maintain the group's morale. If Shane does something bad for the benefit of the group, it's not as damaging as if Rick did the same thing. They need a good guy to look up to. As time goes by, both Rick and Shane realize that this unsettling arrangement is for the best. I think both actors will do very well with that division of labor.