Each time Guerrilla has shown Horizon: Zero Dawn we've seen the same area and scenario. This is usually not a good sign, and apparently hunting robotic dinosaurs is no exception.
A very reliable source of ours claims that Sony plans to announce that the game has been delayed to early 2017 during Sony's E3 conference. Industry insider Shinobi602 heard something similar:
"Well...Horizon: Zero Dawn's getting delayed to early 2017 from what I'm told. Going to look splendid on PS4k though."
Our source told us that Sony is still considering using the phrase "first half of 2017" at the announcement, as they want to give Guerrilla the time they need with the need hardware and push the original PlayStation 4 to the max.
This means that they'll aim for a release in March, with a chance of it being pushed into May. Of course, both our source and Shinobi602's may be wrong, but considering it leaked it wouldn't surprise us if Sony releases a statement earlier than planned. .