The possibility of interconnecting any kind of device to the Internet is driving the adoption of the Internet of Things (IoT) paradigm also in a city environment. Many IoT applications are making the Smart City concept real, offering advanced services to citizens and city administrators. This evolution relies upon a seamless exchange of information among different systems. Exchanged data includes personal and/or critical information, thus requiring proper handling in order to avoid security and privacy issues. At the same time, recent developments in robotics are fostering the realization of autonomous agents (e.g., cars, buses, drones) that do not require human intervention. In the city of the future, many services will rely on autonomous agents. Also, autonomous agents (e.g., robots) will become more human alike, and will be able to show emotions. Therefore, they will replace humans in many city activities. In this paper, we first overview the expected evolution of IoT applications and, then, we briefly analyze the security, social, and ethical issues that are foreseen in a Smart City context.