The future of wireless network generations is revolving toward unlocking the opportunities offered by virtualization and digitization services in smart city applications, with the aim to realize improved quality-of-experience (QoE) and bring several advantages to modern cities. According to the rapid development in the field of network virtualization, we envision that future smart cities will run over ubiquitous deployment of virtualized components that are controlled by artificial intelligence (AI), i.e., the conceptualization of the Digital Twin (DT) paradigm. The key principle of the DT relies on creating a holistic representation of wireless network elements, in addition to decoupling the information pertaining to physical objects and dynamics, into a cyber twin. The cyber twin will then leverage this information for AI models training, and then reasoning and decision making operations, which will be then reflected to the physical environment, for improved sustainability. Motivated by this, in this article, we put a forward-looking vision to the integration of DT in smart city applications, and the intertwined role of wireless technologies as being enablers and enabled by the DT. Moreover, we sketch the roadmap toward identifying the limitations of the DT in 6G-enabled smart cities, and open new horizons for further developments in different design aspects.