Integrating machine actors into daily life blurs the line between humans and machines, presenting opportunities and challenges. Within this context, the field of human-machine communication (HMC) stands at the forefront, poised to explore this emerging phenomenon of human-machine interaction. As we look into the future of this rapidly evolving era driven by machines, this essay discusses how the field of HMC can continue to grow and expand its research paradigm. Specifically, the essay delves into the theoretical foundations and methodological approaches of HMC, addresses two prominent research frontiers centered on social presence and trust, and then examines critical implications of HMC from various perspectives. Throughout the essay, it offers insights into future directions for HMC research.