I think they will let Abraham live longer in the show than the comics. In the comics he was killed by Negan's top man, Dwight. Kirkman has said he regrets killing him off so soon. I guess it will be either Glenn, Darryl, or Morgan that will be killed by Neegan. I think Morgan would be a bit of a easy choice, as he is not really an original, even though he was on the first show. Fans are so mad about Glenn's fake death that I do not think they will put fans through that. Glenn also is sort of the "moral compass" of the show, so I think they will keep him. So, I think Darryl is a very likely choice. Plus, this show is becoming more and more like the comics, and Darryl is not in the comics, so it makes sense that way too. Personally, I think it is Glenn's time to go; but I do not think that will happen.
I believe there is a 0% chance of Rick, Carl, Carol, or Michonne dying anytime soon.
I think one or two other characters like Rosita, Sasha, Tara, or Eugene, will be killed too, but that will not be the "big death." Also, you know a few more Alexandrians will kick the bucket as well. With a few exceptions (Heath, Aaron, the chick doctor, etc.)They are basically used as "redshirts," from Star Trek, or the survivors on Lost that hardly or never spoke.