Well after watching the direct, there is a couple of things against the chorus kids/Rhythm Heaven (although not really)
The most important one, at least to me, is the fact that there won't be any secret unlockable characters, Sakurai is gonna reveal all before the game comes out so there might be 1, maybe 2 directs where he reveals the last characters in the game. Now I always saw Chorus Kids as the perfect unexpected secret character that always seems to be in each game, however even though this wont be happening, it doesnt mean Chorus Kids can't be in, we just have to hope for a trailer in the last upcoming directs.
There's also the fact that so far with these reveals Sakurai seems to be wanting to please a lot of people with highly requested characters, primarily Ridley and K Rool. Rhythm Heaven is sadly not as popular as many other game franchises out there so if he only focuses on highly requested characters they might be in danger.
However, its nothing new, Sakurai has included very highly requested characters before, alongside oddballs that no one saw coming/maybe no one had requested (Wii Fit Trainer anyone?), aka a Sakurai pick.
Now comes the exciting part, the points FOR Chorus Kids / Rhythm Heaven.
First of all, Chrom. Who would think a character from an entirely different franchise could help support a RH char argument but here we are. With Chrom added, Chorus Kids are the ONLY puzzle piece left from the Gematsu leak of Smash 4 (ah this brings back memories), and the fact that Sakurai has stated before that Chrom was considerd/Rhythm heaven data was found in the file, its pretty clear the leak was right, albeit from a very early point of the development of the game. With Chrom coming back, its clear this cut character situation wont lead to a "Forbidden Seven" situation like in Brawl. (Or at least I hope so).
Then there's the fact that NOTHING from Rhythm Heaven has been shown, if there was an Assist Trophy, Stage or Item from a Franchise BEFORE a character from said franchise is announced, you can basically count the entire franchise out of a playable rep. Rhythm Heaven has had luck in that, so if they are gonna show up a new stage or an assist trophy it will likely be after a character reveal like Simon with his stage and assist. There is still the horrible possibility that there is nothing from Rhythm Heaven in the game, but I would rather not dare think of that.
There was an incredible amount of content of Rhythm Heaven in Smash 4 that was strange considering the series had no items/stage/assist, there was the trophies in both versions of the game, and then the music that was added in the miiverse stage (I muted every song except the 2 RH songs lol) and with the miiverse stage gone, for obvious reasons, there's no stage with RH music in it for now.
There is a chance that everything RH related has been cut but it would make no sense to me, as this isnt a dead series, the last game came out AFTER smash 4 did, so its technically still going, and its a series that Sakurai is well aware of.
I would also like to point out that, despite all of the newcomers shown, theres only been TWO new franchises in total added to the Smash family, and of those two only ONE is first party, that being Splatoon. It's kinda crazy but I do feel like nintendo needs to add at least a couple new franchises, Rhythm Heaven could be a new first party franchise for the game. Of course it will need to come with a stage and we go to the next point:
Stages, now Sakurai said theres 103 stages, but I'm not sure if thats a final number, unless all of the next newcomers are all from franchises already represented/that already have a stage (meaning Splatoon and Castlevania are the only new franchises in Ultimate, which to me, doesn't sound like a good idea) and we know theres still newcomers to be announced because he literally said so at the end. He can't just have shown ALL of the stages at this point, its too early. So I do believe there will be more stages to come, there's even already blank slots in the stage selection that was shown:
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Now, sure, that could be for DLC but the thing with Nintendo is, they finish a game BEFORE they think of DLC, and thats what they did in Smash 4, it would feel really wierd to think that Sakurai is already planning DLC even before the game comes out, so I do hope these slots are filled or else it will feel like content that is being held back on purpose.
So I hope for the sake of the next newcomers to not all be from franchises already represented, that there's still stages to be revealed.
The DK pose watching tv that mirrors the Karate Joe pose... eh, I wont really consider it as a point for RH in Smash, I think thats a popular pose in Japan and a very likely coincidence. (But you never know, Sakurai said before the Direct to "excuse him for having red eyes" which in the end was just alluding to Bloody Tears from Castlevania).
So in conclusion, so far we are doing extremely good, and the chances for a RH after this direct has elevated in my opinion.
And for me, more than having a fun character to play in smash, I really want Chorus Kids or whoever from Rhythm Heaven to join because I want the series to get more recognition. It revived Kid Icarus, it could potentially make a Switch RH game a possibility in the future, since Megamix kinda felt like a closing for the franchise, and I really don't want it to end! So yeah more than wanting to hear the awesome songs that RH has while fighting in Smash, I want a character in because of what it will mean to the franchise itself, thats how much power Smash has.