The technological development of construction robots is underway globally. However, current development activities face significant uncertainties, particularly in terms of the definition and management of system requirements, which are primarily based on vague assumptions about the future. Thus, a new tool is required to grasp how construction robots-and their surrounding ecosystems-will be used. This research adopts an unprecedented scenario-based approach to develop and analyze future alternatives for construction robotics in a systematic manner. Hong Kong "toward 2035" is used as an initial test case, and four scenarios of the robot ecosystem, i.e., "Bottleneck," "Age of Iron Worker," "Dynamic Co-evolution of Robotization and Modularization," and "Rise of the Robots," are developed from evidence-based analysis. Scenarios highlight the crucial role of workers for construction robot utilization. Driving forces, opportunities, and challenges are identified for elaborating strategies under each scenario. The integrated scenario approach and findings lay an important foundation for systems engineering processes in construction robotics to develop a new tool for structuring system context and specifying system requirements.