More and more industries are experiencing digital disruption triggered by new technologies for example cloud, mobile, Internet-of-Things, Big Data, and Artificial Intelligence. Majority of applications are predicted to provide cognitive capabilities to amplify human skills and expertise in coming two years. Information Technology (IT) services industry is also shifting from people-led and technology-assisted model into a people-assisted and technology-led model. However, the ever-changing IT technologies, increasingly complicated IT environments, and ever-shortening IT delivery cycles in real world pose great challenges to existing IT Service Management (ITSM) technologies. This paper aims to discuss the trends, opportunities, and challenges in transformation of real-world ITSM in cognitive era and to trigger more practical research work in this exploited area. It firstly reviews the evolution of ITSM and discusses key technologies behind the evolution. Then, it summarizes opportunities and challenges in transforming ITSM with cognitive capabilities in real word. Further, we discuss key enabling technologies to drive the evolution of ITSM towards Cognitive one. Finally, we conclude the paper and envision real-world best practices in this area.