I DONT KNOW MAN, I basically found this video. I typed everything into google translate as the dude calls up the worker at Gamestop to ask about Uncharted for PS4 which he found on the site:
What basically is said is (if im not entirely retarded) =>
In the system of Gamestop, it appears the game is due for 16.02.2014.
However he says that since it's not officially announced, it's likely that it will take until the end of the year and that we will hear more at Gamescom. Or maybe he meant that it will be revealed at the end of this year and is actually slated for 16.02.2014. (Any german that can clarify?)
The fact that its in their system makes him like rather confident that its coming.
How did I find this? I searched at youtube for Uncharted 4 sort by date. Why? Because its 3 AM and I cant think of anything else. I need UC4 ;_;
Take it with a grain of salt as always.
Link =>
http://www.youtube.com/watch?v=Au3wvDWxGJQ