Evero has already proven to be a successful DC with Denver and Carolina.
I know Carolina just blocked Evero from interviewing with Jacksonville, but that doesn't mean in the near future they won't let him interview somewhere else. Especially if Carolina decides to hire a defensive minded coach, which is TBD.
Henderson is a great D-Line coach, but he's an unknown at calling a defense. Evero is already proven and has a history with McVay. So I think the choice would be easy, given Evero would be available.