As I said, there has to be a provocation for Palutena to be revealed in a Direct. Luigi, Sonic, and Rosalina all had a build up to their reveals.
Luigi had year of Luigi, Sonic had the games from Sega, Rosalina was used in a Mario Kart Trailer.
So, unless Iwata straight up says, 'Here's some footage from a specific someone..." and then shows Palutena, there is going to need to be some sort of reason to specifically show her.
That could be a number of things though. A Kid Icarus event, Smash News in general...etc...