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.
I really disliked Carl in S1 and S2, the character was a major spoiled punk and nothing special about the acting. But, in S3, I thought the actor really stepped it up, and the character was much better (Well, at the end he started becoming a bit of a psycho, but, I'm good with seeing where they go with that)
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?