Governance is one of the key differentiating elements between traditional systems and systems of systems. While systems are governed by a single 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 system of systems to voluntarily expel or exile one or more of its constituent systems. Yet, research has not addressed so far the implications and modeling of potential exile into the operational effectiveness of a system within a system of systems and its impacts on the engineering of systems of systems. This paper presents the concept of system exile as a philosophical necessity in the definition of systems of systems, it discusses some visions to measure the risk of exile, and proposes a way forward to explore mitigation techniques.