Assume the role of a Chief Information Security Officer (CISO) for a major financial institution. Draft a strategic roadmap for transitioning the organization's public key infrastructure (PKI) from RSA/ECC to post-quantum cryptographic (PQC) algorithms (such as CRYSTALS-Kyber or CRYSTALS-Dilithium). Your plan must address inventory management of current cryptographic assets, selection criteria for NIST-standardized algorithms, hybrid implementation phases to maintain backward compatibility, and a risk assessment regarding the 'store now, decrypt later' threat model.