Welcome to the forums!I'd like to see Pac-Man announced, if we're to get another 3rd party character.
However, I'm expecting more along the lines of someone a bit more predictable, such as Yoshi. Though, fitting the theme of announcing characters around the time of their game's release, it's safe to say Yoshi won't be announced 'til around May 3rd(The release of New Island). So it's very possible we'll get Ness, or a new Fire Emblem character.
I think Yoshi is a strong contender for the next POTD reveal. However, the topic of this thread actually pertains to who will be revealed at the next Nintendo Direct event, which will be in April. If you aren't aware, all post-E3 Newcomers and Third-Parties have been revealed during a Direct, whereas Veterans have exclusively been revealed via the Miiverse Pic of the Day feature (except Luigi, who I think may have been confirmed during the August Direct due to the Year of Luigi thing).
Sonic was confirmed during October's Direct, Rosalina during December's, and now Little Mac during February. Since Directs exist for the purpose of promotion, it is no surprise that they would show off Smash Newcomers during these events.
Yoshi and Ness will no doubt be revealed during one of the Pics of the Day, as all Veterans (sans Luigi) have. As for Pac-Man, he seems more fitting for E3, given his name and legacy. For April, I could see a Fire Emblem Newcomer, though I'm sticking to Takamaru from Murasame Castle for now.