this isn't a show with a whole lot of happy surprises. I'd be surprised if carol is alive.
I'd be surprised if she wasn't.
The series never showed us a body or a death scene (while Lori's death happened explicitly off-screen, all we get with Carol is she runs off and leaves a scarf behind).
And the series has been quite willing to bring back characters who simply might
have died - this season alone both Merle Dixon and that prisoner who ran into a field of zombies.
I've seen online theories that Carol may have been abducted by whoever was watching her attempt a Cesarian section on a walker back in the second episode (one camera angle implied it was the POV of someone hiding in the bushes). Given she hasn't shown up this seems a plausible way out.
The irony is that Norman Reedus' most notable role prior to being on The Walking Dead
was playing an Irishman in The Boondock Saints
Thought it was an Irish-American, but I never did see those movies.