Well, as I've written in the Seph thread, there are still things left open that favor a Sephiroth reveal. And these things are a collection of stuff that, at least to me, are considerable enough to be taken into account.
S-E's PR will start focusing on everything FFVII a week or two from now, as KHIII is launched and the hype would live on by itself for a while.
FFVII Remake is confirmed to have a re-unveiling this year. And oddly enough, FFVII and IX on the Switch didn't have their release dates revealed by neither Nintendo nor S-E. The only possibilities that a Seph reveal would make sense is in a Direct that feature one of these two issues being resolved. The FFVII launch on the Switch is coming soon, so it's not far fetched to assume that the next Direct will feature it.
The holdoff of new FFVII content is also something that could be dealt with in case Seph gets in the game. We've heard from pro players how the events had people complaining to Nintendo staff about the lack of FF content in the game and them responding that "they were listening".
I, for one, believe that the leaks could turn out true, but I'm not putting all of my eggs in the same basket. To this day Verge only said that Erdrick was the one he heard the most, but never did he take the position he took with other characters that turned out to be true. S-E doesn't suffer this big of a leak so far before launch. And Brave is merely stats that are not final, and could even be a character that is not even from S-E. Cloud's stats in Smash 4 changed considerably before his reveal and launch.
Finally, the different times Sakurai referenced Sephiroth during the road to Ultimate's launch is uncanny, to say the least.
Here's a hype music to go along with it. :3
The best news coming from this is Retro Studios returning to work on the game.
This also means that the game they've been working on for the past few years is near completion and will be revealed soon!!
EDIT: This is why I held off buying DQXI until the Switch version came out. It's confirmed the game will contain additional scenario to the overarching experience. Kinda like a "Final Mix" for DQXI. And yes, the video below has lower quality due to it being a livestream recording.