Let's review.
At the season finale, we had 11 survivors from our team kneeling in front of Neagan. Rick, Michonne, Glenn, Daryl, Rosita, Carl, Maggie, Aaron, Eugene, Abraham, and Sasha.
Morgan and Carol are safe, because they're 'off-site' with the new group from the comic series, "The Kingdom".
Rick & Carl are safe, that is a given, leaving us 9 possible victims. Rosita and Aaron haven't had enough time to become a fan favorite, so I don't think it's one them, bringing us down to 7.
Michonne, Glenn, Daryl, Maggie, Eugene, Abraham, and Sasha
They just killed off Rick's last love interest, so I think Michonne is safe. For some reason, I don't think Sasha is on the chopping block yet. Which leaves 5.
Glenn, Daryl, Maggie, Eugene, Abraham. Eugene and Abraham have both become fan faves, however, Eugene was beaten up by the Saviors already, so I don't think that Neagan would want "sloppy seconds". In the comics, Abraham dies by an arrow through the eye, which the good doctor took in his place a few episodes ago, so it could be Abraham.
Glenn & Maggie have been here since the beginning. Losing either would be a blow to fans, and with Maggie being pregnant, it would be a cruel, harsh death. However, it is Glenn that faces this death in the comics.
This leaves Daryl. A Daryl death would gut the show, and since he's not in the comic book, he could face this death. The one thing that may save Daryl now is that the network has so much merchandise with Daryl Dixon on it, to kill him off makes no sense.
I think it's one of the following three: Abraham, Glenn or Maggie.