One Piece manga creator Eiichiro Oda said during an interview on Thursday that he plans to wrap up the story in four or five years. This information came from Masaki Aiba , who then asked Oda, “Do you know how old the work will be?”
Furthermore, Oda added that “We have to talk about everything whenever my editor changes,” and the editor sitting next to him during an interview confirmed that he already knows the ending of One Piece.
Source: ANN
