This paper identifies key technological gaps in adaptability, energy efficiency, and quantum-resistant security in wireless broadband area networks (WBANs) and proposes a novel Large-Scale Language Model (LLM)-based adaptive WBAN framework that enables ultra-reliable, secure, and self-optimizing WBANs for next-generation mobile health applications. It highlights the limitations of existing heuristic-based designs and presents research challenges for resource-constrained, 6G-ready healthcare systems. The paper characterizes the LLM as a cognitive control plane that coordinates routing, physical layer selection, micro-energy harvesting, and quantum-resistant security in real time. It provides a comprehensive review of WBAN architecture, routing strategies, and security mechanisms.