I saw someone mentioned Gunvolt. I played both his games and they were pretty cool. I don't think he will be Playable though, but I'm very Confident he's gonna be a Mii Costume
Considering the results of that video, it seems to me that the focus of 1st parties really is drawn by the same handful of picks. There doesn't seem to be much deviation there.
I just think it's interesting. There's no shade to be thrown or anything, I just think it's interesting that it seems consistent anywhere you go with the 1st party options being quite similar from fan to fan.
I must admit that I skipped through it because I'm an old man watching Dateline, but I think an interesting concept would be boiling down each character not only to a moveset potential, but also looking at "what factors make X more plausible than y?"Just seems to me like we can clearly acknowledge that not all characters are in equal standing, but among 1st parties I wonder where the fanbase would say they all stand.
To Answer your Question, I think in terms of what characters have more factors going in their favor, I would say
Rex & Pyra and Isaac are the Top Tier characters. Rex has Sakurai Grace and love for him, and Nintendo has Shown lots of Xenoblade love recently with remake, even if Rex might not be in that. Isaac has rumors of something happening with his series (due to the trademarks and all that), and also had Backlash towards AT Inclusion that I believe Nintendo heard, which could be something to consider
If it were not for the Spirit Event so close to FP2's Finalization (And it also coming back in February) I would add a Gen 8 Pokemon to Top Tier as well, due to it being Pokemon.
Waluigi is also up there, though i don't know if he's the type of character that will get a Fighter Pass all to himself. if Bonus characters are a thing, then He would be top tier, due to the Huge Backlash from his AT reveal, and also just him being a Mario character, meaning he be recongized.
Paper Mario, Dixie, Bandanna Dee, and Euden fit somewhere below Waluigi. Paper Mario has all the rumors, and if he wasn't another Mario I think there would be huge merit to his inclusion. Dixie and Bandanna Dee are popular and if there are bonus Fighters They become more likely, but eh. I understand why Euden does get looked at, with his series being a Big Nintendo step into Mobile market, but otherwise that's all the appeal i can really see backing him up