I'm going to try making a prediction, though it'll likely be more pessimistic than my previous attempt (where I guessed Min Min, Steve, Geno, Ryu Hayabusa, Dante, and Impa after Steve's reveal). I don't think I'll make a prediction Fighters Pass after CP9 is released, though - it seems like it would be easier to guess when there's only two spots left.
Monster Hunter: I'll preface this by saying that I'd prefer to see Dante, and I feel like he's at least as likely. However, I could see Capcom wanting to promote Monster Hunter, especially with Rise coming out, and given that Monster Hunter is (by my understanding) extremely popular in Japan, I could see them giving it the red carpet treatment - twenty or thirty songs, at least as many spirits as what FF7 got, a stage that showcases as many monsters as possible, each alternate costume being a different set of armour instead of a palette swap, an extremely detailed gimmick...
I haven't enjoyed Monster Hunter from what I've played of it, but I could see them being the next character.
Ryu Hayabusa: if he doesn't make it into Smash, I'll be a little baffled. Koei-Tecmo seems to be the biggest Japanese third party that isn't in Smash at this point, he's got history stretching back to the NES days, and Koei-Tecmo is close enough to Nintendo that they've worked on multiple spin-offs and one main entry in a Nintendo franchise (Fire Emblem: Three Houses)
As for the last character, I figured we'd end on a tamer note - I was thinking it would be a blatantly promotional Nintendo character, but no Fire Emblem games have even been announced (I know "Fire Emblem bad" is a little overplayed, but every time a character seems to be added to promote a Nintendo game, Fire Emblem seems to take priority - look at Roy, Corrin, or to a lesser extent, Byleth), while Pokemon Sword and Shield will be two years old by the time that this DLC ends. (and we don't seem to get new unique Pokemon characters through DLC, if all of the DLC so far is any indication - that could easily change, but maybe the Pokemon Company or someone else involved is hesitant to do anything with DLC?)
While I was thinking that Impa or another Zelda character could be added to promote Breath of the Wild 2 if that ever comes out, it doesn't seem like the Smash Bros. development team has any interest in adding a Zelda character. (the series has its 35th anniversary this year, and its been 20 years since a new unique Zelda character became playable in Smash) Maybe we could get someone else (for example, Elma being added to promote a remastered version of Xenoblade Chronicles X), but I'm guessing...
Crash Bandicoot: Activision seems to be doing everything in their power to promote Crash Bandicoot and bring him back into the spotlight, and Smash Bros. arguably has a better line-up of Playstation all-stars than Playstation All-Stars. (along with 2/3 of Microsoft's big franchises) I don't know much about how closely Nintendo and Activision are connected (beyond the Skylander/amiibo hybrid during the Wii U days), so this seems like the biggest stretch out of my predictions.
I'm not super familiar with the Crash Bandicoot games (I've finished the third game, Crash Team Racing, and Wrath of Cortex, and I've started Crash Bandicoot 1 and 2 but reached a wall in both of them), but I figure that he wouldn't have a super crazy moveset or any ridiculous overpowered gimmick - it would be fairly straightforward, like a character from the original game or Melee. Maybe we could get Coco as an echo fighter for an added bonus, but that seems unlikely. (I don't see her being an alternate costume - if Lucina's any indication, even the slightest change in hitboxes results in a costume being split off into its own character, and it doesn't seem like Crash and Coco would have the same hitboxes)
Out of the characters that I'm predicting, Crash is probably the one that I'm the least confident about, but two of my four original predictions (Geno and Impa) were abruptly confirmed as Mii costumes or post-launch spirits since the last time that I did this (which seems to severely decrease their chances), and I figure that we're only getting one Capcom character in this fighters pass, so there aren't a ton of characters that I'm confident about at this point.
So this is how it would turn out:
This wouldn't be ideal for me, since I'd probably prefer about a dozen different Capcom characters over Monster Hunter, and while I appreciate Ninja Gaiden and Crash Bandicoot for their historical impact, I don't have much of an attachment to either series (I'm not a fan of games that are frustratingly difficult seemingly for the sake of being frustratingly difficult - I've only beaten one Ninja Gaiden game, it was apparently the easiest one, and it was still frustrating at times). However, I figure that this line-up (or at least a line-up like it) seems most likely. (Though I'm fine with being wrong)
I didn't include any Namco-Bandai characters because that company seems unusually hesitant to include their characters in Smash, even though they worked on the past two/three Smash games. I'd think that we'd get a Tekken character at some point, but I figured that character would be Heihachi, who was stuck as a Mii costume again. As much as I want Agumon, or I'd be interested to see how KOS-MOS would work, I don't know how likely they are.
Maybe the Chosen Undead (I think that's the player character from Dark Souls?) is possible, but I haven't played enough of Dark Souls to know what would set them apart from any other swordsman, or a Monster Hunter character. (all I know about Dark Souls is that there's a lot of rolling and stabbing/slashing, the gameplay is frustrating/clunky, your attacks don't do much damage against the behemoths that you're fighting, and you have to stop and wait for a while if you want to heal, which pretty much sums up my experience with playing Monster Hunter)