What happens if the Mysteries are insufficient for the number of communicants?
Not enough bread, or not enough wine? I'm not sure what happens if the bread runs out. Judging from what I've seen at my church, though, if the wine runs out my priest will simply pour more wine into the Chalice on the understanding that the newly added wine will become the Blood of Christ by contact with His Body, the consecrated bread. Thus he needs not reread the epiclesis prayers over the wine as he pours it into the Chalice.