Let me be the first Paper Mario hater to admit to being wrong on this. As I believe the game to be on the same level as amiibo Festival, Starfox Zero, and Ultra Smash, I predicted it would fare no better than them, so 500k at most lifetime (I might try to find the prediction thread for reference). At first it seemed like I was gonna be correct, as the game didn't even break six figures on it's launch week, however the game had unexpectedly decent legs.
As of the latest chart update (April 15th), it sits at 780k, beating out the aforementioned games and my prediction. Wont reach a million but will probably end up between 800k-900k. By no means an amazing number, still falls short of all it's predecessors, but it's not a bad number either for a low budget game like this, definitely made Nintendo money. Thankfully there's no need to fear that this could mean they'll continue with the series like it is, as they already said they were dropping the Sticker Star formula.