Basically fiats can't destroy fiats as the government itself won't care about them becasue they can be easily be regulated for the benefit of the government. The government in some years to come will gather these stable-coins for their benefit, so, the fear of the government destroy these stable-coins will not even exist. The decentralized stable-coins should be those that government might fight but still yet might not see the light of the day as these decentralized stable-coins can't be trace.