If you look at the guts of the XBoxOne, or at least those of which we have been so far exposed to, it seems plainly obvious to me that this is a device for the long haul, meaning it will likely evolve to add new functionality/apis/ecosystems every year.

And frankly, we've reached a point where that is not only feasible, but sensible.

You only have to look at how the 360 has evolved platform-wise from launch.