This chapter delves in detail into the use cases (UCs) widely assumed to be addressed by the 5th generation (5G) wireless and mobile communications system, and the related requirements. It takes into consideration and aggregates the requirements from different bodies like the International Telecommunication Union (ITU), Next Generation Mobile Networks (NGMN), and the 5G Public Private Partnership (5G PPP). The chapter is an analysis of the 5G ecosystem evolutions that are needed, and the novel value chains that can be expected for some UCs. It introduces the main service types considered for 5G and presents key 5G UCs as considered by NGMN and different 5G PPP research projects. The chapter also delves into the likely ecosystem evolutions from a 5G mobile network perspective, with emerging value chains of mobile network operators (MNOs).