As the company's product manager, your boss (the marketing manager) is concerned about the future success or viability of the product line you oversee. She wants to make sure that you understand the reasons that could cause a popular product to become an unpopular product.
She asked you to meet with her and discuss three products and/or services that seem to have declined in consumer demand, severely hurting these other firms. To keep this from happening in your own firm, your boss has asked you to describe some examples of this phenomenon and your opinion on why the popularity declined.