The commercial vehicle industry stands at a pivotal juncture as it transitions from Internal Combustion Engine (ICE) to more sustainable powertrain technologies such as Fuel Cell Electric Vehicle (FCEV). While much attention has been devoted to powertrain development and hydrogen infrastructure, this paper addresses a critical yet often overlooked aspect: the profound implications for commercial vehicle braking systems. Central to this study is the loss of the exhaust retarder's substantial power dissipation capacity when converting from ICE to EV. This change necessitates a fundamental reimagining of braking strategies, as regenerative braking alone proves insufficient for prolonged descent scenarios common in commercial vehicle operations. This limitation becomes even more prominent when moderate-size batteries are used, as is the case for Range Extenders and FCEVs. This research provides a comprehensive analysis of: • The technical challenges in replacing ICE-based retarders with alternative systems in FCEVs; • Comparative performance of traditional retarders versus regenerative braking, with a focus on long-descent scenarios; • The requirement to keep traditional retarder systems as fail-safe devices, and the importance of achieving well integrated designs; • Prospects for automated, integrated control systems that optimize energy recuperation and brake usage. The paper also explores the broader implications of this technological shift, including regulatory considerations, economic impacts, and necessary adaptations in fleet management and driver training. By addressing the intersection of FCEV conversion and braking system adaptation, this study aims to contribute valuable insights to vehicle manufacturers, fleet operators, and policymakers. It underscores the complexities involved in the transition to sustainable commercial transportation and proposes innovative solutions to ensure safety, efficiency, and environmental sustainability in the evolving landscape of commercial vehicles. This research not only fills a crucial gap in current literature but also lays the groundwork for future studies in smart energy utilization and integrated vehicle control systems, positioning itself at the forefront of sustainable commercial vehicle technology.