Carl means drama, and is a central character from the comic, so he's not going anywhere.
That he's a central character from the comic is irrelevant, Andrea is one too and that didn't save her ass last season.
When Jeffrey DeMunn wanted to leave they simply made Herschel the new Dale and Carol is already closer to comic-Andrea than show-Andrea ever was. They can find a better child actor and create a new Carl if they need one.
The difference between Carl and the other characters is that he's Rick's son
--the main character, so his evolution becomes part of Rick's development/journey, and cannot be dismissed as easy as Dale, et al.