This paper introduces a formal framework to evaluate post-quantum cryptographic (PQC) readiness by analyzing how security protocols interact across different network layers. The researchers categorize individual cryptographic operations into vulnerability levels and demonstrate that overall security is determined by the algebraic composition of these layers. Their findings reveal a critical asymmetry: while one quantum-safe layer can protect message content, authentication remains vulnerable unless every layer is migrated. Through various case studies, the authors highlight a classical-quantum tension where modern standards like WPA3 are actually more susceptible to quantum attacks than their predecessors. Ultimately, the study provides a structured methodology for organizations to prioritize migration strategies and manage the risk of "harvest now, decrypt later" threats.