Correction, one person thinks Tom Nook is going to be shown off. That person also believes we're getting 5 or more shock newcomers, just for the 'yuks.
A handful of users, mainly the GameFAQs bandwagoners who were so sure Dixie was coming in February, have managed to convince themselves that this was no big deal, and that she's a shoo-in for the next reveal or whatever (and if that doesn't happen, it's gonna be "Oh, she's obviously unlockable."). Could that happen? Yeah, and it wouldn't really be fun, because it would put K. Rool fans on the defensive all the way up until release. "He has no chance! One DK Rep! Part of Mario! Irrelevant!" and so on. Whatever the newcomer is, though, I have a feeling it won't be promoting anything, since it's a Smash Direct, not a regular Nintendo one. This is the opportunity to show off the Takamarus, Palutenas, or, if we're lucky, K. Rools of the game.