To be honest, I’m still shocked that it hasn’t happened yet at all, why hasn’t Nintendo given KOEI TECMO a fighter yet? It just doesn’t make any sense, the only KOEI TECMO content in the game is content that’s not even fully owned by KOEI TECMO themselves (AoC, P5 Strikers, FATAL FRAME) as they joint own those with Nintendo and SEGA/ATLUS. Is it because KOEI TECMO franchises are too lewd and also that some of them are based on historic figures which wouldn’t count as video game characters? Like maybe Yuri Kozukata in Smash is all they could think of, but FATAL FRAME is lewd too…WHAT ARE THE RULES DAMMIT
I like to think it's because Nintendo and Sakurai like to catch people by surprise, even with the most obvious characters and a Koei Tecmo character seems VERY obvious for Smash.
When I think about this, I look at Namco. Ever since it was confirmed that they were working on Smash 4, a Namco character seemed inevitable. In fact, I'm sure a lot of people other than myself thought that a Namco character would be one of the first characters to be revealed. Instead, Pac-Man wasn't revealed until close to the game's release and even in this game, another Namco character, Kazuya, wasn't included until near the end of the second FP.
I know this may sound like another crazy theory but I gotta admit, even though I was hoping Hayabusa would be revealed at E3, I also wasn't surprised that he wasn't. Because one thing I have noticed with all these new characters is that none them had anything leading up directly into their reveal. I compared this to the Hero situation back in 2019 but one difference that I overlooked was that Dragon Quest XI for the Switch was coming out months later after he was included in Smash. So when I look at the timeline of everything surrounding Hero, it was:
Earlier that year: Dragon Quest XI Definitive Edition is announced
Middle of that year: Hero is confirmed and released for Smash Ultimate
Later that same year: Dragon Quest XI Definitive Edition is released
Nothing happened in the same month. It's all spaced out, as if it's a one-at-a-time kind of thing for the character or series.
Hayabusa would have had both his games released
and his Smash reveal in the same month, which usually doesn't happen. Couple that with his in-game birthday that just happened to be on E3 and yeah, that would obviously lead to some speculation and anticipation of a character that I don't think Nintendo and Sakurai would want. In fact, Sakurai himself admitted that he doesn't want to set up speculation for any character for Smash, which is why he doesn't even mention what games he plays. Heck, he can't even mentions names of games or other developers without fans thinking it means something for Smash.
So this is why I think there's a good chance that Hayabusa could still very well be that last character. The Master Collection was announced earlier, then released just now, and the next Smash reveal will be later. Hopefully, that'll be him.