A new game is unlikely to be announced. A character for Smash or the confirmation of a port (such as the first Ori game) are more probable options, especially the latter.
I'm thinking there's more to it than that. Miyamoto was reportedly going to show up at the Microsoft conference, but there were flight issues and that's why it was shorter than planned. I highly doubt he would go through the trouble of showing up if it were were a port.