Funny how the brand loyalty didn't keep all the 360 owners with Xbox One.
The 360 had a LOT of casual owners who bought in for Kinect and not much else. Those people wouldn't have had much brand loyalty.
Kinect Adventures sold something like 24 million units, and the Kinect itself around 30. It was enough that Xbox sales shot up substantially in year 5 and kept rising through year 6.
This is abnormal, and no other system followed that sales curve. MS brought in a lot of casual gamers doing this, but unfortunately much like Nintendo with the Wii, they didn't have a coherent strategy to hang on to these people. The same people that bought a cheap box with Kinect Adventures in 2010 are absolutely, positively not the same people showing up to buy a $499 XBox One system at launch.
Microsoft centering the Xbox One's Kinect around "TV" and then killing it off within about a year didn't help matters.
Without that audience that bought in for the 360 Kinect, the core lifetime 360 audience is probably closer to 50-60 million, which probably isn't all that far off from where the Xbox One will end up before MS EOL's it.