20 million, let alone anything higher, makes absolutely no sense.
Instead of going ahead with something dropped on a windows podcast by "someone close to microsoft" who heard something from an "internal source" that she can't verify, maybe we can just use actual numbers and a bit of common sense.
20M sold through, that would mean at the very least 21M shipped. 1M extra is really a bare minimum.
The only solid number we have for shipment comes from MS's FY year report for the second quarter of the XB1's life (ending March 2014), and that was 5.1M shipped total. This would mean that they've shipped ~16M XB1 since then. Keep in mind that during their investor call in April 2014, they mentioned a channel inventory drawdown because of excess supply.
During that period and until March 2015, they've shipped 13M XB1+360. So the only way you can imagine they've shipped that many XB1 would be that they've basically barely shipped any 360, which is really not believable for a second. For the same period (april to March) a year prior to that they've shipped 6.5M 360, down from 10M.
They were also at "almost 10M shipped" in mid-November 2014, which means that:
- a significant portion of what they've shipped (10.1M between April and December) was 360 consoles.
- they'd need to have shipped another 11M since then, which would be up ~100% YoY.
Now if we move onto actual sales, the XB1 was at 9.7M as of November 2015 in the US. That would likely put them at 11.2M December included, or thereabout.
So the question is, where are the remaining 9M? First, it would mean that the US share is at ~55%, significantly down from the 60% at launch. But major markets have at best kept the same pace than the US, and it's been slowing down in many others. Second, that would mean that they sold 7.5x their launch (Nov-Dec 13) numbers in RotW, compared to the known 5.2x in the USA. That's just not possible.
And then we have these figures:
France 420k as of Dec 14
Germany 380k as of March 15
Japan 64k as of now
Spain 80k as of June 15
The remaining markets are much, much smaller ones than France or Germany, and there's really no indication that the XB1 (and the brand in general) is performing well in these markets.