Spoiler warning for Season 6 of The Walking Dead, The Walking Dead comics, and maybe Season 7, we’ll see.
The Walking Dead TV series likes to reuse events from the comics with different characters, and having Negan kill Abraham would follow that logic.
In the Season 6 finale of The Walking Dead, new villain Negan (Jeffrey Dean Morgan) introduced himself by killing a major character with a baseball bat wrapped in barbed wire.
Abraham is already dead in the comics — he took the arrow-to-the-head that killed Denise (Merritt Wever) on the show.