Quantum computing is reshaping the cybersecurity landscape, but Post-Quantum Cryptography (PQC) alone cannot guarantee long-term resilience. This paper examines the limitations of current approaches and the growing threat of hybrid attacks amplified by artificial intelligence.

Drawing on practical cybersecurity and engineering experience, the authors argue for a shift from fragmented, reactive defenses toward integrated, multilayered security architectures that combine cryptography, hardware, software, networks, and continuous monitoring. The paper explores what financial institutions and critical infrastructure operators need to consider today to build systems capable of withstanding tomorrow’s quantum-enabled threats.