This makes me believe that every newcomer dlc will be bundled with a stage like Ryu. Like Inklings and Inkopolis, King K. Rool with his ship.
My first thought as well. Ryu already sets a pretty decent precedent for that, so the fact that Super Mario Maker was a game to get a cross promotional unique stage yet Splatoon hadn't (in spite of the crazy marketing that game was getting by Nintendo standards) is pretty suspect in retrospect.