The next event is going to be announced 11 hours after the presentation.
As Flyboy was pointing out, they have announced events earlier then scheduled before when there's a new character to show off.
Also, the more I think about it... the more possible Ayumi ending the pass feels to me.
On one hand, the FDC remakes are still digital-only, so I don't know if they would be desirable promotional material. They also weren't given the full nine yards in localization, not including all the European languages that most major Nintendo titles receive, assumedly as a way to reduce the risk of localizing a game in a nicher genre...
On the other hand... Well, first off, we know Sakurai loves this series, and yet it got neither collumn nor pic of the day release day celebration tweet nor spirit event. Second off, the remakes were announced in the exact same Direct further DLC was confirmed, so the schedules line up pretty darn well. Third off, this entire pass has had most characters be in a sort of "Scrapped once; back again" limbo - with ARMS content, Tekken content, Xenoblade Chronicles 2 content all being confirmed to have been considered/dismissed earlier, while Steve (and allegedly Sephiroph) was in negotiation limbo for a long time). Ayumi is a character who was considered/dismissed before, with both of the reasons for her dismissal no longer being concerns (her games are now worldwide and Sakurai no longer has reservations about offending fans by making a non-fighter fight in Smash). And , fourth off,the final character being in their own presentation makes me think it was someone too niche for a general direct - someone they want Sakurai to do some salesmanship for, which I think Ayumi would fit.
It's not confirmed. It's not even neccessarily all that likely. But I now feel like Ayumi would just... fit quite nicely with the scenario.