Haha...definitely something that could hurt the manga/anime business as a whole. I have no idea how much of a drop off sales of the WSJ volumes, manga volumes, and associated merchandise changed after DB ended. Hard to imagine that there wasn't a drop in interest and sales (casual fans of all other series only buy the WSJ volumes for One Piece material => I have a couple volumes where One Piece has a color spread). But I have to imagine Oda's work is inspiring a new generation of mangaka. One Piece is so long we are seeing people with new publications referencing Oda as a source of inspiration. Of course it's selfish to expect multiple "once in a generational" series to come up so quickly, but great series will be published.