The imminent advent of a Cryptographically Relevant Quantum Computer (CRQC) poses an existential threat to the US financial infrastructure. Current payment rails including FedWire, CHIPS, and ACH rely on RSA and ECC standards that are mathematically vulnerable to Shor’s Algorithm. This facilitates "Harvest Now, Decrypt Later" (HNDL) attacks, where encrypted data is intercepted today for future decryption. This paper evaluates the migration to NIST-standardized Post-Quantum Cryptography (PQC), specifically ML-KEM and ML-DSA. We analyze the architectural challenges of integrati ng these primitives into ISO 20022 formats, focusing on the trade-offs between increased packet size and sub-millisecond latency requirements. By proposing a phased migration framework using Hybrid Cryptographic Wrappers, this research provides a roadmap for maintaining regulatory compliance under NSM-10 while preventing a systemic collapse of digital trust and the associated multi-trillion-dollar risk to the US GDP.