A key element differentiating traditional systems from systems of systems is governance. While systems are characterized by belonging to a single governing authority, systems within a system of systems are often independently governed or governed by fully empowered entities. Such independence is a necessary condition for the autonomy of each constituent system and for enabling the concept of belonging. At the same time, the capability to be autonomous and the voluntary nature of belonging, enables a constituent system to voluntarily abandon the system of systems it belongs to as well. Yet, research has not addressed so far the implications and modeling of intended abandonment into the operational effectiveness of a system of systems. This paper presents the concept of system abandonment as a philosophical necessity in the definition of systems of systems, it discusses some visions to measure the risk of abandonment, and proposes a way forward to explore mitigation techniques.