The world is flat, because it becomes increasingly mobile, fast, connected, and secure. People expect to move around easily with their mobile devices, keeping close communications with their partners and family, enjoying the versatile usage models and infinite contents, and without worrying about the device and data management. This paper describes investigations in the trends of mobile OS architecture over the next decade by focusing on the major commonalities. Based on the findings, it also reviews the characteristics of today’s mobile operating systems from the perspective of architecture trends.