I don't think it will ever outsell PS4 in the US. Sony is not really putting up a battle right now. They have not just turned their backs of course, we still had the BF bundles, and the current 4 pick 1, but that is just the minimum as people have been trained to expect better deals in the holidays.

If things start to get troubled looking Sony will take a much more aggresive approach. They already said in post E3 2013 interviews they were prepared to launch at $349 had MS announced $399. So they have plenty of room now with production cost even lower, to take the battle back to MS.

Next year Sony will be launching a full on assault of AAA titles nearly every single month. This will culminate with the big daddy Uncharted 4. They also have massive plans to bolster their media capabilities to match and surpass XBO. PS4 will be getting PS Vue, and a massive overhaul to its local media and DLNA capabilities in the comming year.

Finally, in the land of hypothetics. Sony still has major franchises that can debut on PS4. I fully expect Gran Turismo to be shown next year, and it will be coming with genre defining partenerships, and exclusive deals. It will also be the poster child of project morpheus. Together GT and Morpheus will begin a new era in video games, and PS4 will be the only place to experience, the revolution.

And that is why I think XBO will not only never catch PS4, but will stall, ...and fall, to a dracmatic deficit.

Hard to believe it, but sustainability of XBO sales into 2015 may well hinge upon $50, specifically whether the MSRP permanently drops to $349/$449 or the temporary sale on all XBO SKUs indeed ends.

What I have a hard time believing, is that there will be equal or greater demand for the XBO core SKU than the PS4 at the same $399. The $499 Kinect bundle at this point almost doesn't even merit mentioning.

At $330, I was tempted to pick up an XBO holiday bundle, paired with additional Target deals ($50 gift card) even though I currently have no desire to play on more than one platform with the current software catalogs. At $399, with no free games or added incentive, the XBO suddenly drops right off my radar once again. This is not to say that I represent the typical consumer, but at pre-holiday prices, the incentive to buy an XBO simply isn't that great and won't change until some of the key exclusive titles affiliated with the XB brand are released.

Never ever not in this world. Just look objectively on what it took for the X1 to manage PS4 like sales for a month and you'll understand its short term and they wont be able to do it month after month.

Impossible to really tell before we see at least a three months trend starting from November 2014. During last gen it happened different things in different years: sometimes Halo (or any other big system seller on any platform) launch and/or BF sales were revealed as just Xmas sales in advance, other times the momentum created then was kept or even increased.
Not to mention that this is a function of not jut one variable, XBOne sales trend alone, but two, PS4 sales trend too.

Nothing impossibe.  Its was a dozen factors that led to X1 sales, most will not be present in to the new year.  Sounds rather simple enough to me to arrive at its temporary.  

Well, some people are swearing MS would be ready to bleed money for years to make it reach and keep US leadership, I don't believe it, but who knows, we saw more bizarre things happen. Although against them happening again there's the fact that Nadella is a well-balanced guy, while Ballmer was a paranoid obsessed not only with money, but also power, control and domination.

If Sony dont match the price, I guess it should be done on the 2nd half of 2015.

Sure but some are sensible and know better, while they will eat some loses trying to stay relevent.  But to maintain PS4 type sales all year even in NA alone would be financially catastrophic for the xbox division.   

NPD:

X1: 1.2 million

PS4: 800K (compared to 1.14 million last year,let that sink in)

Also using results from the last 10 NPD to conclude who wins the next one? I don't think that's common sense buddy:).