Back in the 1980's and 1990's, Nintendo was one of the most popular and influential video game companies in the world, having released three consecutive consoles (the NES, the SNES, and N64) that were among the best of their respective generations, selling numerous units and having some of the industry's best and most-beloved games (as well as some of its worst and most-reviled).
However, after that, they began to fall behind in the early 2000's, most notably as Sony and Microsoft entered the video game industry and Sega, the other major video game company of the 80's and 90's, ceased production of consoles. While Nintendo certainly is still a very prominent and influential presence in the world of video games, they no longer enjoy the position of supremacy that they once had.
Why is that? I am not a business or economics major, nor have I been following video game news zealously in recent years, so what can anyone else say about this? Why has Nintendo fallen behind other companies, and can they ever regain their former glory?