Even the xb1 and ps4 have an expiration date. Sony and Microsoft both have 10 year plans for their systems, so even they will dump them eventually. The game companies are just beating them to the punch this time. The ps4 just recently saw its second year, so in about 3 more years, we'll likely see the ps5 and not long after, the ps4 will die out. The life cycle of any system is centered around the evolution of technology and how quickly developers adapt to take advantage of it. That's just how it works.