My humble attempt at guessing Negan's victim:
1.) Since Negan was somewhat taunting "you're taking it like a champ" after his first hit .... it's the kind of taunt that you tell a dude rather than a lady.
2.) Since it's obviously not Rick or Carl, that leaves us with Abraham, Glenn, Darryl, Aaron & Eugene
3.) IMO it's not Daryl nor Glenn, since both are fan favorites - even in past seasons, people have literally promised to riot if Daryl dies.
4.) So, we're left with Abraham, Aaron or Eugene ...... cases can be made for all three to be saved/killed-off.
5.) Aaron is still a "non-character", not much screen-time to fully know him in the series ...... he's safe, I think.
6.) Abraham has gotten considerable screen time moreso with his love triangle. In movie nuances, that means he's due to get killed-off. But .....
7.) Negan's words " You're taking it like a champ" is usually reserved for timid/cowardly dudes ....... I think it's Eugene who meets up with Lucille.
Bye Eugene. I think.