One Piece: World Seeker was expected to release sometime within the year as part of the One Piece series’ 20th anniversary, but it appears to have been delayed to 2019. [Thanks, Gamestalk and @tendten40767586.]
The information comes from the Vol. 90 release of the One Piece manga (with additional confirmations here and here) but keep in mind that it isn’t official until we hear from Bandai Namco, but with three months left in the year it wouldn’t be too surprising if they needed more time to improve its quality.
One Piece: World Seeker is in development for PlayStation 4, Xbox One, and PC.