There is no law that says they must remain in business, since they all failed in their theoretical mission, there is no reason for them to exist. They have the option of liquidation. The govt. can take over the rating system de jure, since this makes it clear that they are the de facto, decision makers. Their status as privately owned and operated companies is the only thing that gave them credibility. The govt. can pass any law it wants with our accomplice courts, like ordering debt issuers get govt. agency approval, but those who take fiduciary responsibility seriously will not accept garbage with a triple A rating. This is not a slippery slope of course , it is contraction of a fatal disease.