<p>The grain yield of wheat is the output of the grain-filling process, which is persistently interconnected with crop physiological processes. Under terminal drought, grain filling is based on remobilization of the stored assimilates as well as current photosynthesis, mainly of the flag leaf. Therefore, the flag leaf is a premier organ of photosynthesis that plays a pivotal role in delivering a substantial amount of carbohydrates for grain filling. However, a substantial gap in knowledge still exists as to which metabolic processes are regulated effectively in remobilizing the stored assimilates from plant leaves, particularly flag leaves, to developing grains under terminal drought. Thus, in the present review, we discuss the existing knowledge on wheat plant remobilization, particularly the flag leaves functions, as well as the control of antioxidant defense systems under terminal drought. Moreover, many hormones play an active role in the maturation of plants under terminal water-limited conditions. Thus, the roles of phytohormones such as ABA, cytokinins, and ethylene in response to terminal drought are also discussed in this review. The results of this review provide guidelines for how efficient and judicious the use of resources could be for improving remobilization and sink capacity to reduce the rate of flag leaf senescence and achieve a relatively high wheat grain yield. The importance of improving root traits and root system architecture (RSA) to increase performance and drought resistance in wheat is also discussed. The role of a variety of state-of-the-art approaches, such as high-throughput genotyping and phenotyping, in identifying drought-resistant genotypes/varieties, as well as a multitude of artificial intelligence tools, such as machine learning (ML) and deep learning (DL) models, which are currently used to predict the impact of drought stress, is also discussed in this review.</p>