Firstly, we don't "know" XB1 is under tracked by 600k based on shipment numbers. Thats just your hypothesis.
Secondly, MS does not "usually" ship 1M extra units. As far as shipping goes, all MS can do is meet demand. They can't ship out consoles to stores if those stores still have a lot of stock, cause those stores will not request for new shipments to replenish their stock. So how many consoles are shipped ties into how much demand theer is for the console.
Having said that, I think its extremely unlikely that Ms ships almost 5M consoles in the last two months of the year. Especially when you consider that there is only one territory that they stand a chance of even having great/respectable sales. And that is NA.
So for MS to have 4M in sales in the next two months, you are basically assuming that 3M of those sales will come from NA. Thats reaching if you ask me.







