In this article, we propose a concept of an "adaptable access system" as future access system architecture. First, current issues and trends in communications networks are shown from various points of view, to discuss essential items for a future access system. Next, to set the basic direction of research and development for physical network infrastructure, three visions in the design of future access system architectures are shown. Based on the three visions, three technological targets (key concepts) for realizing the adaptable access system, active single star, servicearea-variable minimum cellular, and access system virtualization, are derived.