You will need to determine if the product will be initially phased out over time through economic allocation, using methods such as discounting and for what duration. If indeed you are assigning monetary values such as economic discounting I would suggest running a consequential LCA (https://consequential-lca.org/clca/why-and-when/) with economic market allocation, identifying such discount rates based upon the current state of demand for your product and general competition over time while also possibly incorporating any future redesign of the product to be phased in if that is possible.

I would also suggest you use some form of system dynamics software that can simulate supply and demand so that it can give you a visual representation of the system to be studied. VENSIM PLE is quite good at this and its free: https://vensim.com/

This provides three things:

1. You will be able to see over time how the predicted future market will affect your product through simulation

2. You will be able to run multiple scenarios very easily such as Low, Baseline and High demand etc.

3. You will be able to determine the optimal product obsolescence, phase out and replacement period when demand is low.

Great! Thanks for the answer. The other key element is the technology that can be associated with the product. Any emerging innovation (by the same company, or through licensing) can short-cut the business plan based on the suggested simulation. Key and sometimes difficult decisions to be made here.

I do not believe that programmed obsolescence can be quantified, this problem has to do with the social nature of technologies. If each company plans in a different way the obsolescence of its products, there is no way to establish indicators. This is typical of globalization. For this to happen, several of the organizations that control world trade would have to agree and it definitely will not be possible to do so. For me, programmed obsolescence is another indicator of the existence of a world where sustainable development will not be possible beyond the great powers that control the development of science and technology and obviously world trade. For those of us who live in the developing world, this process is the clearest sign of the decadence of capitalism.