AI systems that can construct detailed internal representations of their environment offer a number of advantages. Such “world modelling” enables systems to work in a more dynamic and effective fashion, updating the models, and associated parameters, as new information becomes available. It also makes for more robust reasoning and decision-making pathways, resulting in more transparent and more flexible planning capabilities. Achieving optimal world modelling will require progress in a number of areas, including neural-symbolic integration, continual learning and embodied AI. What are the breakthroughs we can expect to see in world modelling in the next 5, 10 and 25 years, and how will these affect the performance of AI systems at these junctures?