No planned paid DLC at this time

Splatoon is a pretty great shooter, and over time, it's added more modes, weapons, and levels. Next month will see its first major patch to add in better matchmaking, and for now, all of the content given out so far has been free.

Hilariously enough, Splatoon's co-director Tsubasa Sakaguchi spoke to Eurogamer, and noted that Nintendo was "worried" about the players who reached the level cap of 20 so quickly. He goes on to state, "When we were designing Splatoon, reaching level 20 was going to take quite a lot of time. Learning the game mechanics with the gyro sensor - we thought that would take a lot of time. In that sense we're surprised that people have reached the level cap in such a short time. We're actually really worried about those people - worried that they're still sleeping and eating!"

As far as paid DLC goes, Sakaguchi notes that "at the moment, we're not planning any paid content." He goes on to say that new stages and weapons will be "slowly" released. As I've stated in the past, I think the entire "Season 1" of Splatoon will be free, but next year and beyond, they'll likely add on more premium content to supplement the server costs.

After all, they did say that they aren't interested in annualizing the franchise, and Nintendo generally sticks to its guns on stuff like that.

Nintendo's bright future with Splatoon [Eurogamer]