With advances in end-user devices and other technologies, the demand for immersive experiences that seamlessly blend the digital and physical worlds will be significant by the end of the decade. To support these, 6G networks will need to deliver unprecedented capacity, low latency, energy efficiency, and cognitive capabilities to manage vast radio resources. The potential of artificial intelligence (AI) to enhance the physical layer and reach these goals has been demonstrated in previous works. In this white paper, we explore the frontiers of machine learning (ML) to improve features beyond the physical layer (PHY) and further enhance the native AI air interface (AI-AI) envisioned for 6G.