I don't think three years should be a problem considering (from what I remember) the last games (I.e. 3DS and Wii U) only took about two or so years. Edit: Did some checking on the development period. Earliest start of Smash Bros. 3DS/Wii U development: March 2012 after completion of Kid Icarus: Uprising Main game released (Wii U): December 2014 So less than three years from start to finish of the main game. And now it's been over three years since the last game was released. Even accounting for DLC (ignoring that a full development team is unlikely to have been working on just that), they could have started working on a new game as late as February 2016. It really seems like they have plenty of time to have created a new game.