Empty spots discovered via a data mine of Super Smash Bros. Ultimate hints at an unannounced third Fighters Pass.
Pyra and Mythra officially joined the Super Smash Bros. Ultimate roster last week. That leaves two more spots open on the current Fighters Pass. The final two additions will be announced before the end of 2021. According to Smash director Masahiro Sakurai, that will be it for this chapter of the franchise, and there will not be a third Fighters Pass.
However, a discovery made via a Smash Ultimate data mine begs to differ. The initial discovery made by Mizumi revealed 16 dummy spots in Ultimate's World of Light. Since the addition of Pyra/Mythra, YouTuber PapaGenos has revisited that discovery and noticed something interesting. Despite being a transforming fighter, Pyra and Mythra each occupy their own slot on the roster.
That means there are still five slots left of those 16 dummies, but only two fighters left to announce. It could be a case of the final additions having an alternate form, like Pyra, or maybe even two, and they will fill the slots themselves. However, there are also five blank spaces to fill in the stage selection screen. This suggests that Nintendo still has five Smash Ultimate DLC announcements to make, not just two.
If there is any truth to this at all, it would mean the third Fighters Pass would be a smaller one and include just three new characters. It's also entirely possible that the characters are already in place. It was previously revealed that it took years to make Minecraft Steve a part of the Smash roster. Sakurai also revealed that he keeps figures for unannounced characters in a locked drawer in his office.
Short of breaking into Sakurai's office and cracking open that drawer, the only way we're going to know how many fighters are left for sure is by waiting for Nintendo to tell us. That might take a while. It is in no rush to complete the roster hence the gaps between reveals usually being months long. It will likely be summer by the time the next character is announced. Feel free to speculate wildly on who it might be between now and then.