I think he's saying that the archbishop would maintain his seat even if most of his congregation formally revoked their membership in his church, that his presence does not depend on the number of his parishioners.
Ah, ok. But I wonder about this. Perhaps if it became increasinly evident that the Church of England had less and less support, then the position of Archbishop of Canterbury may begin to be regarded as a position of little importance.
When the Reformation took place in England back in the 1530's, the position of the Archbishop of Canterbury still existed, but went from a man of catholic ideas to a man of protestant ones. But of course the decision to change religion came from above, and not from below. If the change were to come from below, then I wonder what would happen to such positions like that of the Archbishop of Canterbury.