Amazon US, Amazon UK, and Amazon Germany appear to be taking pre-orders for the upcoming game. According to their listings, they have put a release date for the 31st of December, 2018 which is clearly a placeholder. Nintendo themselves did not mention a release date but we guess if you don’t mind pre-ordering this early on, you can go ahead and do so.
In addition to not mentioning when the game will be released, Nintendo also stayed mum on the details about the game. Previously it was rumored that the game could be a port of the Wii U version of the game, except that it will feature some new content similar to what Nintendo did with Mario Kart 8 Deluxe.
However what we do know based on the trailer is that the game will feature new characters from Splatoon. Whether or not these are the only characters remains to be seen, but their addition to the roster has been pretty much confirmed.