So MS just released figures and they shipped 6.6m Xbox consoles during the holiday Q.
My estimates (though they are irrelavant to overal Xbox console sales if you notice the title) are that 4.5m are XB1 and 2.1m are 360. This puts 360 at around 86.9m and XB1 around 11.9m.
However you spin the ratios, it's a fact that combined they're at 98.8 million shipped.
We have 95.5m sold, that leaves 3.3m on shelves which is a lot for dying 360 and XB1.
FYI, I don't think XB1 is undertracked, just 360, heavily. (like 1.5m~)