Achieving circularity in product development requires extending product lifespans through upgrades, reuse, and modular design. Industrial update factories provide a promising environment for implementing these strategies across multiple product generations. However, this entails significant complexity in anticipating future requirements, managing systemic changes, and supporting long-term design decisions. This paper proposes a structured approach to interoperability across product generations to support decision-making for circularity. By distinguishing between white box (past), grey box (in development), and black box (future) product generations, the framework serves as a transformation model, enabling a systematic analysis of generational interdependencies and resolving goal conflicts in a sustainable manner. Building on this, a scenario-based methodology is introduced to identify potential future influences, assess their relevance and criticality, and derive actionable design requirements in the early stages of current product development. The approach enhances anticipatory capabilities, reduces lifecycle-related risks, and promotes design flexibility by integrating cross-generational interoperability into product architectures. With this future-oriented decisions can be operationalized to extend product lifespans and increase circular value. Overall, the concept strengthens strategic planning capabilities in circular product development by formalizing generational interoperability as a design objective to support more resilient, resource-efficient, and future-ready products.