Maria Bello as Magna (It’s a dead theory but consider her a placeholder.)
How come Maggie and Ezekiel are under also starring?
Lauren Cohan has yet to resign. So at the least I expect her to be downgraded to guest starring appearances, most, also starring. Same with Negan, though that's cause JDM won't be around as much considering Negan will be imprisoned.
I mean, Daniel Salazar got demoted from series regular in Fear, so demotions can happen.