Some of these technical barriers include:

  1. Limited scalability
  2. Limited privacy
  3. Lack of formal contract verification
  4. Storage constraints
  5. Unsustainable consensus mechanisms
  6. Lack of governance and standards
  7. Inadequate tooling
  8. Quantum computing threat
  9. … and more.

Source: Fundamental challenges with public blockchains – Preethi Kasireddy – Medium