I have developed two Theories for the post-126 era in the comics. Here goes:

Firstly, I think the decision to keep negan alive could lead to a Carl/Rick rift. Sort of like TV Shane clashed with Rick over Randall, but the main difference being carl will most likely not try to sleep with Lori or kill Rick.

My second theory-- one I find much more interesting, even if it is a long shot-- is that "somebody" kills negan. In the time leading up to it, Carl will have been very outspoken that he thinks Negan deserves to die. Then somebody goes to check in on Negan and finds him dead. Nobody knows what to think... Except Rick. Rick knows Carl killed Ben. Nobody else does. But here's the catch: Carl says he didn't do it. And, much like Carol on tv, we never SEE who did it. This would be a neat possibility. I always thought there was more to get out of the Ben and billy story. And didn't Rick almost let slip to Andrea that it was Carl? And one more thing: does Carl know he killed Ben? He had that nightmare I assume was him remembering the event, but did Rick ever explain to Carl that it actually happened? This story has a lot of possibilities. I really hope this happens.

Anyways, those are my theories. Lemme know what you think.

 

I don't think we have to worry about Carl becoming a villain outright. He's a good guy. He definitely has a dark side and knows what needs to be done. (dad, I have to do this. You're wrong.) But he can control said dark side and has shown his humanity is stronger than ever. (the way he comforts I-forget-his-name's son) Plus, he absolutely idolizes his dad, to the point where I think his approval matters to him more than anything else. So I don't think we have to worry about carl kicking Dwight in the balls and talking over the saviors or anything like that. If they chose to make Carl's darkness the main point for a while, it could be that his own dark side becomes his own worst enemy. (struggling the way Abraham did when we first met him, for example)

I DO think it would be interesting to find out if he remembers killing Ben or not. If somebody kills negan, and Rick accidentally says that it wouldn't be his first time. Andrea still doesn't know. Would create an interesting little dynamic, IMO.