storyteller
Superstar
Got some sad news brehs. Oda has recently confirmed that One Piece is about 80% done -
Eiichiro Oda Reveals How Close 'One Piece' Is to Completion
Hate it has to end, but I guess nothing lasts forever.
So that means at most probably another 5 or 6 years. Enjoy the ride while it lasts, because I think once it's over, it's over. Doubt Oda will care to do any spinoff or anything like that, he puts all his ideas into the actual manga.
With the way Oda's team miscalculates how far they are through a single arc, I'd stretch the estimate even longer.