I feel like they might quickly realize that relinquishing control and spending more money on a manager buys an incredible amount of peace of mind and security. If they give him what he wants and step aside Ashley may actually win something and he likely won't have the fans causing any level of grief. Meanwhile, Charnley will have the easiest job in the world and be paid handsomely for it.
In fact, they probably already realized that in the last 6 games.
Giving Rafa what he wants is a ticket to relative anonymity, which I think they will both be happy with.