Emerging Fifth-generation (5G) mobile networks and associated technologies are expected to provide multi-service wireless applications with diverse specifications intended to address not only consumer-based smartphone applications, but also the needs of various vertical industry markets (e.g., healthcare, education, energy, mining, agriculture, manufacturing, and so forth). This paper extends 5G networks' technology orientation towards attaining economic value for all key 5G stakeholders, including customers, mobile network operators (MNOs), equipment vendors, public institutions, private enterprises, digital business start-ups and other third parties. Although several surveys and tutorials have discussed business models in connection with 5G networks, there is no comprehensive study on business models for emerging 5G networks from the MNO's perspective. In this survey article, we present and investigate key advances on business models for 5G networks and 5G MNOs in particular, from industry, use cases and research community perspectives. The paper focuses the theoretical business model concept from both strategic management and technological innovation perspectives. Thereafter, we discuss conventional business models for MNOs before presenting particular disruptive business models which can be considered for rolling out 5G networks with an aim to improve business efficiency. Additionally, the paper explores the emerging network deployment concept of private 5G networks and their related business models. Finally, we present some of the open research challenges and provide possible guidelines for implementing 5G business models based on various countries' socio-economic status and relevant 5G use cases applicable in a specific context of emerging economies.