I think negan is going to force rick to kill Glenn, rather than Lucille him. He will threaten to kill Maggie and her baby if rick doesn't do it, so he will have no choice.
Glenns actor told the media that the show doesn't always follow the comics so people shouldn't assume he will be Lucilled... people assume this means someone else will in his place, but I think it means he's going to die a different way at the hands of someone else (rick)
Someone will still probably be Lucille, likely Abraham.
