Is AI the Fourth Pillar of Infrastructure? Infrastructure doesn’t go away — it layers. And today, AI is emerging as a new foundational layer alongside compute, storage, and networking. Erik Torenberg interviews a16z’s Martin Casado, Jennifer Li, and Matt Bornstein breaking down how infrastructure is evolving in the age of AI — from models and agents to developer tools and shifting user behavior. We dive into what infra actually means today, how it differs from enterprise, and why software itself is being disrupted. Plus, we explore the rise of technical users as buyers, what makes infra companies defensible, and how past waves — from the cloud to COVID to AI — are reshaping how we build and invest. Timestamps: 00:00 Introduction to Infrastructure 00:48 Defining Infrastructure and Its Components 02:27 The Fourth Layer: AI Models 06:34 The Evolution of Infrastructure 17:46 Developer Tools and the AI Wave 21:27 Data Engine Systems 22:11 Defensibility in AI Infrastructure 25:28 Expansion and Contraction Phases 27:09 Challenges in AI and Infrastructure 28:32 AI Models and Generalization 30:59 Thoughts on Andrej Karpathy's Talk on AI 34:09 AI and Human Expectations 36:18 The Role of Developers in the AI Era 40:31 Synthetic Data 43:17 AI Agents 45:16 Vertical Integration vs. Horizontal Specialization Resources: Find Martin on X: https://x.com/martin_casado Find Jennifer on X: https://x.com/JenniferHli Find Matt on X: https://x.com/BornsteinMatt Stay Updated: Let us know what you think: https://ratethispodcast.com/a16z Find a16z on Twitter: https://twitter.com/a16z Find a16z on LinkedIn: https://www.linkedin.com/company/a16z Subscribe on your favorite podcast app: https://a16z.simplecast.com/ Follow our host: https://x.com/eriktorenberg Please note that the content here is for informational purposes only; should NOT be taken as legal, business, tax, or investment advice or be used to evaluate any investment or security; and is not directed at any investors or potential investors in any a16z fund. a16z and its affiliates may maintain investments in the companies discussed. For more details please see a16z.com/disclosures.