If an organization has a 5 year refresh cycle (~time to implement a new IT system), and there exists a quantum computer with a sufficient number of error-corrected qubits by 2027 [1], an organization/industry has 5 years from 2022 to go quantum-resistant: replace their existing solution with quantum-resistant algos (and, in some cases, a DLT with a coherent pan-industry API) and/or double their RSA and ECDSA key sizes.

[1] "Quantum attacks on Bitcoin, and how to protect against them (ECDSA, SHA256)" https://news.ycombinator.com/item?id=15907523

Which DLT/blockchains without PKI (or DNS) will implement the algorithms selected from the NIST Post-Quantum Cryptography (PQC) round 3 candidate algorithms? https://csrc.nist.gov/projects/post-quantum-cryptography