3rd party titles.
3rd party titles continues to push PS4 units, while Xbox One doesn't get the same level of 'push'.
In 2015 there will be even more "big" 3rd party titles releasing, and if the trend continues - PS4 will come out on top, again.
-Dying Light
-Evolve
-Final Fantasy Type-0 HD
-Project Cars
-Battlefield: Hardline
-Mortal Kombat X
-The Witcher 3: Wild Hunt
-Batman: Arkham Knight
-Metal Gear Solid V: The Phantom Pain
-Naruto Shippuden: Ultimate Ninja Storm 4
-Madden NFL 16
-FIFA 16
-Assassin's Creed Victory
-Star Wars: Battlefront
-Untitled Call of Duty Game
-Rainbow Six Siege
-The Division
It is worth noting, that a lot of these games is 'current gen only'.
Exclusives.
And J-Stars Victory VS+
17 announced retail games that will come to Playstation 4, but not Xbox One - all in 2015. (I am probably forgetting some)
Playstation 4:
1st Party games - increases PS4's lead
3rd Party games - increases PS4's lead
Xbox One:
1st Party games - decreases PS4's lead.
2 steps back, 1 step foward.
I fully expect Japan to have a much higer baseline in 2015.
(This list has not been updated for a few weeks)
The PS4 is launching in China in January, which should give the system a good boost. It'll be cheaper than the X1 in that country and going by the polls and forums, the PS4 is preferred way more. With a good launch library, it should easily do substantially better than the X1 over there.
It would be dump to think, that Playstation would go through another Holiday with a $399 price tag.
Here is my 5 reason. What do you think?