It doesn't matter what you're due under a contract if the counterparty is insolvent. Medicare beneficiaries are going to have to accept reduced benefits and higher fees. This is unavoidable due to demographic changes.
the society reneging on its contract today means that the current taxpayers will lose the trust in the society and in particular will be significantly discouraged from paying taxes, etc. as they would lose belief in the society keeping its side of the bargain in the future.