First off I want to say that this isn't meant to be some "DOOM Thread." The X1 will certainly sell well enough to reach 30 or 40m and it is not about to fall into a black hole. Also, I never owned in iPod or a Zune.
Simply put, the X1's biggest failure was losing the "It device" fight with the PS4. I say this is the biggest failure because it is one that is going to hold the Xbox One back for its entire lifetime. At this point MS will have to move mountains to ever catch up to the PS4 because consumers see it as the inferior product, and no one wants to buy the loser.
My point is perfectly illustrated by the story of the Zune. Before it released I remember seeing this joke on Saturday Night Live: “On Tuesday, Microsoft released their iPod competitor, the Zune. Zune, as in ‘Hey, your Zune isn’t as cool as my iPod.’“
The Zune launched at the same price as the iPod with the same storage capacity. However the iPod just did what it was meant to do better: Play music. The iPod was smaller, easier to navigate, and simpler to load up with songs and use. Yeah the Zune had these other features but they really just distracted from its main purpose...Sound familiar? Price drops, new features - it DOESN'T MATTER. People bought the iPod and now by the PS4 to do what they bought them to do.
This is what needs to be sorted out before anything else.