Serious question/theory:
Sakurai said in the August Direct "We will reveal the
designs of all of the characters before release"
Could it be that the final direct reveal a certain number of characters, trailers and all, but then he just shows us who the remaining characters are and says "you'll have to play to find out!" or something stupid like that lol?
For example, in line of this leak:
Smash direct reveals Isaac, then Ken and Shadow as the final echoes, followed by Banjo and Kazooie. By the end of the direct, the banner fills in and we see Mach Rider, Chorus Kids and Geno are also on the banner, but he states that he only wanted to reveal who the characters are, but its up to us to see how they play.
I know this doesn't fight against leaks fully, but at least he gets to announce all of the characters.
Edit: thinking about it more, I honestly think its a GOOD reason for people who like surprises still. It also helps reduce the directs runtime if its an issue about how many announcements people think it will have.
DLC characters being free for Online subscriptors is super likely considering Mewtwo in Smash 4.
Hell, maybe it explains incineroar