I actually think they have, but I reckon they will "ask" him to move upstairs, rather than give him an ultimatum. Even Wenger, as stubborn as he is, will realise that it would be a chance to walk away from the day to day management with some dignity.
There's still a lot in the press about Arteta, although he has no real experience. Tony Adams has proved that he can't manage a club, he's tried & failed on several occasions, although it would be a fairy tale ending, Mr Arsenal returning. He walked away from Wenger some years ago saying that Wenger wouldn't listen to anyone; that's probably why our defence is so bad, Wenger won't listen to Steve Bould. Bobby Pires is still at the club, but again, he has no experience.
Dyce & Howe have both proved they can manage teams on a budget, but what we need is somebody who can manage "stars & egos", not just average players.