This paper examines upgradability through modular product design, aiming to extend lifecycles and promote cross-generational use. It builds up on a preceding work, a systematic literature- review identifying four fields of action in future-robust product design. The paper itself contains an in-depth interview study with 17 experts from industry and research to validate and expand the literature-based fields of action. The results provide insights into the application and employment of future-robust product design, with a focus on adaptable product architectures.