If we don't have a proven winner, big name coach ready to come in, Miles needs to stay. It wouldn't make sense to fire a coach, and that coach be the best name on the list of available coaches.
I'm assuming they have a guy in the wings. You're right, to make this move without a plan would be crazy.
And why would we ever think the AD who made the moves at Duke during the Duke Lacrosse scandal would ever jump the gun and not have a plan?