European financial authorities have warned that advanced quantum computers could undermine blockchain cryptography before the technology achieves commercial viability. The Joint Committee of the European Supervisory Authorities stated in its Autumn 2026 Risk and Vulnerabilities report that quantum threats to communications, transactions, and blockchains could materialize earlier than expected. Approximately 6.9 million Bitcoin, valued at roughly $586 billion, currently sit in legacy wallets vulnerable to potential quantum attacks according to Cryptoquant data. While EU regulators did not specify a timeline, a recent IBM report projects quantum computing will be in use within four years, intensifying debates over securing legacy crypto assets against future cryptographic breaks.