## 6 Analysis of Findings and Selected Research Approach  
Besides what is commonly perceived as necessary product design aspects, e.g., product quality in terms of long life and recyclability, there are additional design aspects which in the worst case potentially can/will abruptly stop, or even kill, a product's lifecycle (or at least any new sales as well as requiring a re-call of not yet sold but distributed products). The existential product design aspects found in the research relate to circularity, cybersecurity, and availability (which is part of designing the structure of actors participating in the value chain/network and thus a very critical part of the planning for the whole lifecycle of products). Thus, extensive knowledge, understanding, and the ability to plan for a whole lifecycle are needed to successfully bring products to market and then be able to create and capture value for many years to follow. This includes the selection of one or more adequate business models supporting cyclic, sustainable, long, and extendable product lifecycles. Ifthe products are not prepared (i.e., designed) for the future, unnecessary and unanticipated risks may become of an existential nature instead of a problem or issue to resolve. Designs for long and extendable lifecycles will likely have a higher initial cost as, for instance, hardware components may be more expensive but profitability, competitiveness, and ecological and societal sustainability will be better in the long run. Besides the hardware aspect, there is the need for further detailed design and the selection of manufacturing and assembly operations. In particular, assembly design is of vital importance in the implementation of circular products. This is due to the fact that the re-using and re-purposing of a product is always the first step to try, prior to disassembly, to conduct any necessary maintenance or upgrades. Thus, there is a need to shift management thinking towards total lifecycle cost and apply a whole lifecycle perspective as the requirements and design, development, and test phases are just a small part of the lifecycle and, in fact, are just the start of the lifecycle.  
Concerning the problem, i.e., \"the issue of identifying crucial design aspects that, if neglected, can halt a product's lifecycle or hinder future sales\", it has been initially addressed, and several existential design aspects have been highlighted. Further, regarding the research question, i.e., \"how can a product lifecycle include existential design aspects and ensure they are adequately incorporated into the resulting product outcome?\", an initial model has been crafted ensuring the transformation of existential design aspects into actual requirements through iterations between the requirements and design, development, and test phases.  
Pertaining to the choice of research approach, the participatory research well supported the crafting of the initial model. Other possible choices would have been action research or sequential case studies. To continue the research towards achieving changes and further development with the verification of the model in the target organizations, action research will likely be used instead of participatory research as the action research approach targets achieving change (as well as further refinements of models).