Honestly I think you guys are in for a big surprise, and not just with December's results but also the new normal in 2017 and this supposed narrative of the XB1S now being the more appealing product (because 4K UHDBR drive I imagine?).Exclusives are not the reason as Gears 4 did poorly and we have no info on how Horizon 3 performed after launch.
You could say having a big third party game like BF1 bundled in helped, but with the info we had back in October, those bundles only did 42K out of a total 329K. I think this is simple. Xbox One S is seen as the more appealing product right now. Whether or not the PS4 family can outsell the S after the Pro launched is something that needs to be seen. Also the post holiday crash for both XB1S and PS4.
Imo the XB1S benefited from a combo of early adoption of new format (which I think has already dried up), attractive bundled up software (in the pre-Holiday and Holiday time frame) and killer deals, particularly in Sept/ Oct (the uncertainty around the PS ecosystem introduced by the Pro probably being a plus too).
Just looking at an anecdote: Amazon (just another vendor at this point, let's not generalize from there. The interest is that we have a 5-10% marketshare vendor with actual sales rankings which are updated fairly frequently.)
If the product (XB1S) in itself, regardless of deals, is more appealing, why would the PS4 (UHDBR drive-less) with a 7 + months old title bundled still dominate then?
Are Amazon buyers a special "breed" that don't know "what's up"?