I think it would be a mistake for the writers to turn Carl into Shanelite even worse Merlelite, or even worse again govenerlite.
I don't want a punk to be the new group antagonist, and they would be ruining a perfectly good character that really represents the future of the group.
Man I really don't want to end up wanting Carl to get taken out by
walkers by other means. But the tone at the end has Carl on a path that doesn't look good, when he dropped that Sheriff's badge at the end, is that the writers foreshadowing Carl is done being on the side of the good guys.
As for Rick he dabbled with the dark side and came back from it, I really like how Michone and Rick are interacting, if both survive long enough, I see a possible relationship down the road for those too.