In a clip shown during the Walking Dead panel at New York Comic Con, we saw Negan threaten more brutality than the murder we still have not had revealed to us. Of course, what Negan is joking about doing is really unlikely.
In this new clip, Negan makes a comment about the importance of having a "right hand man" and then saying that it's hard to function without out. Then he drags Rick into his trailer with an ax.
And look, all of this is an obvious set up to Rick losing his hand, like he did in the comic. However, Robert Kirkman has repeatedly said that it would be a lot of work for the show to do the same thing. A couple of years ago, on Sundance's The Writer's Room (via Wepaint), Kirkman "To be perfectly honest, the practical difficulties of having a guy who doesn't have a hand is extremely complicated in the comic and would be impossible in the show."
This was corroborated by Andrew Lincoln, who said in 2015 that he actively campaigned to lose the hand, but the special effects supervisor shouted him down. "I campaigned two seasons ago when the Governor was around... I was saying, 'You've gotta do the hand guys!'" said Lincoln. "And Victor, who was in charge of special effects, just said, 'No, no no no. Anybody else but not you. It will cost a fortune with green screen and blue screen.'"
Which makes it sound like if Rick loses a hand, it's only economically feasible if Rick's not going to be around for a while. That's wildly speculative, of course, and it's more likely that it's not happening.
Kirkman walked the "impossible" statement back a bit, saying in a Reddit AMA:
To clarify, I think cutting Rick's hand of when we did was GREAT for the comic. It's just that in another medium it would be harder to pull off, we cheat in the comic because things aren't moving. You can't do that on the show. You'd see Rick not being able to reload his gun, and things like that.
The CGI of cutting off Rick's hand would be expensive, but we did it with Hershel's leg so if we felt strongly about Rick losing a hand, we'd do it.
So the question after watching this clip is: how strongly do the writers feel about it now? Wait, no. The question is still "WHO DID NEGAN KILL?"