Twitter user @noctulescent has discovered that the pixilated text on the title screen (which as Sakurai stated was the mode they couldn't talk about yet.) can be deciphered frame-by-frame. They discovered that in both Japanese and English the text reads "Spirits".



Now, a weirdly common theme we've been seeing in character reveal trailers is of character being "killed".
We saw it in Ridley's trailer with both Mega Man and Mario and, more importantly, we saw Luigi literally get his ghost (or "spirit") ripped from his body in Simon's reveal trailer.



Now a small detail I noticed was the way the Reaper holds Luigi's spirit in his hand, almost to infer that he's collecting them. This almost immediately reminded me of The Subspace Emissary, where characters are also "killed"
and their Trophies are collected by the main villains.



Now could these "character trailers" actually be, at the very least, a hint that Ultimate will feature some sort of Adventure/Story mode? One where the narrative is that fighters are getting their souls stolen, rather than their trophies? This would also make sense as the Smash games seem to have been moving away from the characters being toys or trophies.

Another hint to a possible Adventure mode is Rathalos. Sakurai mentioned that along with being an Assist Trophy, Rathalos is also a boss character and even shown him being fought in a new stage. (4:00 in the video below)



But something odd is that this "stage" isn't given a proper introduction as it's clearly new. It doesn't appear in the stage select either. And looking at it, it just appears to be a flat plain. No platforms are pits. Rather than a stage boss, could Rathalos actually be a boss in this new adventure mode? We only ever see one character fighting Rathalos in this place, usually there's at least one shot of multiple characters fighting a stage boss, but their isn't here.

That's what I've put together from all of this. If anyone else has a different idea of what this could mean, please share.

Holy crap! Simon Belmont!
Holy Shit! Richter's there too!
Hey it's Crom. The Fire Emblem people should be happy. Oh and Dark Samus too. I'm more excited for her.
HOLY SHIT! K. ROOL! AND HE PLAYS LIKE I IMAGINED HIM TOO.

That's just the characters. My brother and I had a blast reacting to the items and Assist Trophies. We both had a filed day with Bomber, Alolan Exeggutor, Ditto, and the fucking Moon. I freaked out over Shovel Knight being an Assist Trophy, which I think fits just well. Just like Waluigi.