It is expected that the 6G architecture will bring much better network economics and energy efficiency through a heterogeneous architecture that natively blurs the boundary between dedicated network infrastructure and devices. In this context, we foresee that 6G devices will not only be communication endpoints, but they will also be able to act as active network nodes in a data path. As the impetus of climate change calls for a sustainable 6G system design approach toward carbon neutrality, it is time to revisit the power management strategies across devices and networks in cellular systems in a fundamental and holistic manner.