Q seems to be talking in turms of chess and cards. The more impotent the person the stronger the peace. Like when Q awnsered the question about the train crashing haveing a "Bishop" on it, (Higher ranking member of the cult)
"House of cards" is a movie about a politician seeking revenge. But it could also mean members of the suit of cards (or the 4 high ranking families in the cult begging for there lives). The house of cards is about to fall.