Addressing sustainability challenges requires fundamental transformations in electric-ity, heat, mobility, and agri-food systems. To do so, research and policy efforts tend to emphasise the importance of fostering new, more sustainable systems through innova-tion. Instead, this paper focuses explicitly on the “flipside” of innovation: The fate of established systems faced with their potential destabilisation and decline. It is argued that any transition in consumption-production systems involves a combination of innovation (something new emerges) and destabilisation (something old is being challenged). To examine the role of destabilisation, decline, and phase-out for policy and practice efforts, this paper advances conceptual and empirical contributions. Conceptually, it elaborates a framework based on three interacting destabilisation mechanisms: The build-up of pressures, strategic responses by central system actors, and changing commitments to reproductive activities. Empirically, it draws on the historic dismantling of electric tramways in France. The decline of the tramway in France followed a gradual erosion pattern resulting from the long-term degradation of technical, political, and economic conditions, which was accelerated by a relatively rapid phase-out programme. A discus-sion section offers insights on the temporality of destabilisation, the context of phase-out decisions, and the interaction of destabilisation and innovation processes.