Transitions – system changes through natural or sociopolitical forces – have the potential to significantly threaten one’s way of being in the world. In this paper we propose to acknowledge fully this “dark side” of transitions. We posit that transition studies would benefit from cross fertilization with existential risk studies. In order to start exploring such an hybridization, we propose avenues for identifying changes, within human communities’ trajectories, that may threaten their very way of existence. We identify the mourning of immaterial, pangenerational losses as potentially central to such situation of existential threat. We associate these immaterial pangenerational losses to the loss of place, to the loss of ontological security, and to cultural devastation. Finally, we argue that transitions that appear less extreme and dramatic could nevertheless threaten one’s way of being human in the world. As an illustration we use the example of Métabief (France), a ski resort that is currently transitioning to non-snow-based activities.