Whether Carol returns may have nothing to do with the show's story. It's always possible the actor decided to call it quits for some reason.
If not, I agree, we'll see her again.
She'll be back. No character leaves this show without being killed off in some manner. This isn't like a regular 1-hour TV drama series, where a character wants to start a new life and moves or quits his/her job or whatever other kind of soap opera-ish garbage. This is a show about life in a world of Zombies. You wanna leave the show? Okay...here's how you're gonna die!
That Hispanic family left in season 1, if they were killed they didn't show it.
Fair point.