How long do you guys think it will take for One Piece to reach the next 100 million?
2-3 years?
Each volume gets a first print run of about ~3 million, and there's 4 volumes a year. So, 60 mill in the next five years from just that.. (though Oda is being forcibly slowed down a little, so there might only be 3 volumes some years.) and thats not accounting for sales of the previous 70+ volumes. (let alone other merchandise or whatnot.) Sales and viewership also picked up along during the marineford war and people got a lot of backstock volumes then, and there probably won't be another spike like that again.
But all things said and done at its current rate it'll probably hit 400 mill within another 4 or 5 years.
I imagine there will be a huge increase in first print runs whenever the series nears its end in 10 or 15 years though. (It'll probably be doing crazy 4 mill first prints by then ANYWAY… only to inflate more for the finale.)
Still, it'll be catching up to and passing Asterix soon!