With the novelty of the first two volumes (with the big promotion using all those pamphlets) having passed, it could easily drop more.I mean, how could the sales drop even more? It seems like this is about the bottom for a series from a big name author published on Jump. It's published on a magazine with a circulation of millions and has been heavily promoted and yet barely sold more than 10k.
But if it can up the sales to at least 30k a volume, and get some more weekly readers in the magazine, it'll have a chance to go at least 2 years. Reminder that Hinomaru Sumo sold in the 20-40k range for its entire 5 year run (though it had much better reception from magazine readers). Obviously Jump was (and is) expecting more from Kishimoto, but it would buy him some time at least.