The global dairy industry is undergoing a period of expansion and consolidation, alongside heightened critique and competition from non-dairy alternatives. This review identifies four key megatrends within the global dairy sector, focusing in on the socioecological challenges associated with each. The megatrends were identified through a literature review of recent publications within the dairy science and social science fields, as well as a review of grey literature from intergovernmental and institutional reports. Key findings include geographical range shifts in production and consumption of dairy milk from the Global North to the Global South; intensification of production agendas that strive for mechanisation, standardisation, and corporatisation of the sector; increasing awareness of the ecological impacts of intensive dairying; and finally, disruptions to the sector driven by plant-based milks and, potentially, synthetic milks. We identify under-researched socioecological challenges associated with each of these trends. Although dairy milk may be homogenous in its final form, the sector remains heterogenous in its impacts across spaces, places, and scales, as increasingly intensive dairying systems fundamentally reshape human–cattle relations. The combined impacts of these trends bring into question the mythologies of milk and the assumed desirability of ever-expanding dairy industries. Our review finds that the future of dairy is not clear nor uncontroversial and that more attention needs to be directed to maximising and broadening the social benefits of the dairy and dairy alternatives, minimising the human and non-human costs, and limiting contributions to global climate change.