Speaking with GameReactor, a Naughty Dog representative indicated that Uncharted 4: A Thief’s End is still in the early stages of development.
The rep made the comment on the topic of collectibles appearing in the hotly anticipated PlayStation 4-exclusive sequel, commenting, "Collectibles are maybe in the game. We’re pretty early in development. We are thinking about it."
While this may amount to nothing, it’s interesting to note because the game is scheduled for a release in spring 2016; if Naughty Dog is still ‘pretty early in development,’ then it seems unlikely Uncharted 4 will meet that projected release window.
Elsewhere, the rep also said that Naughty Dog is still testing to see if various features will work in the game or not:
"Typically we pull things in and out and see if they fit while we develop a game. It’s the same with Uncharted 4."
Read our Uncharted 4 impressions from E3 2015 here.