I agree with Jeffrey Dean Morgan as a excellent choice for Negan. I've only read the first bunch of comics(maybe through season 2), so I've only read comments on what Negan is about. But Morgan seems to have nailed it. Most charisma we've seen from a villain yet.
Also agree with Brickhouse on the sudden population increase. I think I'd be more annoyed except for the heavy foreshadowing that's been kicked out. Jesus saying how their world is about to get much bigger, the many many comments about how isolated the Alexandrians have been since the fall. It makes sense that people cluster(even if they're forced to do so), it just feels odd after so much empty.
As for the sacrifice... I'm voting Abraham. His open defiance during the speech, plus the idea of taking the down "the biggest guy on the yard" to send a message AND the fact that from what I've heard Abraham is already supposed to be dead. Eugene would also be a possibility since he's an easy kill(and I think there's a storyline for him we' haven't seen yet, how was he captured, what did he tell the Saviors?). Either would be a cop out on TWDs part, but thats my vote. If they want the hyperfans to lose their shit, Daryl...Glenn...Michonne. They were all on that side of the line that Negan was walking(and Eugene, who gave Rick the bullet recipe before all this, which potentially ends his story arc). Per the comics; Abraham is already dead,Glenn should die,Daryl doesn't exist, and Michonne and Eugene have more storyline. So, its a crap shoot. Michonne's death could potentially do the most damage to the group... But it could be anybody, Hell even TWD producers may not have decided yet.
I hate cliffhangers, but this one was done right.
Can't figure out where they're going with Carol. I thought bringing back Morgan was a great move, but his development has really made him into a hindrance. Don't know exactly what they are developing him into but TWD is sure taking their time about it. Its hard to tell whether Carol will "recover" from her breakdown(if that can that actually be called a breakdown?) but I don't know how having another "Morgan-type" will work. At least Father Gabriel is starting to make his bones. I like the actor so I kinda hated seeing him be such a worthless pita.
P.S. Anybody else hacked off about the fact that Ricks group never seems to tie up captives with their hands behind them? All of their enemies seem to do it right.