DLC, probably
which is, in my opinion, not a big deal. Dlc content is just a cheap way to get extra cash from gamers, for things that are normally unecessary.
The only dlc content I ever bought, so far, was Super Luigi U for NSMBU, which is in fact an entirely new game, and a bunch of Just Dance songs. Most dlc content are just overpriced and useless in the sense of completing the game experience. I don´t need, for example, extra maps on CoD or extra characters on Injustice to full enjoy the game.
Now, if they skip local multiplayer.... then it will be a shame.