According to a post on the Sony blog, it seems that the Sony and Naughty Dog want all gamers to be able to play the game at once, and have since ramped up production of the physical copies of the game. Because of this additional manufacturing, the title will be delayed by an extra two weeks meaning that it will instead be launched on the 10th of May, 2016.
According to the blog post from Shawn Layden, “As you know, Naughty Dog is wrapping up production on Uncharted 4: A Thief’s End with the game on track to go gold and into production later this month. In an effort to meet the considerable worldwide demand, and to ensure that all gamers worldwide have the opportunity to play the game on day one, we have chosen to postpone the launch of the game by two weeks to allow for extra manufacturing time.”
He adds, “We know this news might be disappointing, and we are sorry to have to make you wait a little longer to play Naughty Dog’s latest. The good news is that the game is phenomenal — we are fully confident that it will be worth the wait and the team at Naughty Dog is eager as ever for you to experience Nathan Drake’s final adventure.”