My Theory for the Finale
This was my theory before the finale aired.
In the episode, they made it obvious that Abraham and Rick can do the bullets as well. That leaves the choice between Abraham or Eugene. In the comic books, it took five whacks of Lucille to kill Glenn. I am thinking it has to be someone bigger than Glenn. That would be Eugene or Abraham. I am thinking Negan would take out the big guy. I still think it is Abraham. "Bitch Nuts!"