Not sure if this is meant to be snarky or not, but I suspect that is what will happen. The original AC's wife is actually a coach herself and could easily step in. It needs to be someone who is adept at calling pitches if HC were to be out, so there needs to be some skill there (I know I certainly couldn't do that never having played ball before).
let the Catcher call the pitches. they have been relaying signals for some time now, and probably have a pretty good idea of what to call when, and especially what each P in the rotation has / doesnt have