Very interesting, I wasn't aware 360 was closing the gap, much less by 2.6 million in the last year.
Should be a fascinating race to watch from this point on; the platform totals page has Xbox 360 at 49 million in NA, not sure how much of that is in the US though.
EDIT: Nvm just read the article; "The Xbox 360 sold 45.14 million units lifetime in the US. The PlayStation 4 needs to sell another 14.79 million units to surpass the Xbox 360 in the US."
The Xbox 360 is most likely going to win this battle by the end. Unless the PS5 launches at a really high price and Sony faulters at its launch like they did with the PS3. If they do that the PS4 will have better legs. However, I don't see them messing up like they did with the PS3.