Okay, so now that the Banjo thread has become a Social thread and this thread has calmed down, I'd like to register my thoughts about what yesterday means for the last remaining two DLC characters.
First things first: with what we got, arguments like "sales", "current relevancy" and "western reps" should be officially dead. Joker got in because Sakurai likes P5, not because of PQ2 and a possible Switch port, Banjo is currently in limbo and Hero, while technically inspired in the most recent DQ game, is also an amalgamation of 33 years of the series, with things that most westerners aren't really familiar with.
Sure, these points can help or hinder a character, but on their own they don't mean anything. Not anymore. Nothing is set in stone. The one thing all three characters share is that "they were thought to be impossible" by fans.
That was the more objective part. Now, a few opinions of mine:
While there is no rule saying that a company can't get two DLC characters, I do think Sega, Square Enix and Microsoft are pretty much done for the Fighter Pass. It would be naive of me to say anything is impossible at this point, but I do think it's unlikely.
Along with that, Sakurai is trying to appeal to different parts of the fanbase, as well as people from outside of the core Smash audience (which so far is working well imo). So I think they will go for different genres for the last two DLCs.
This means having both Joker and Hero could be a hit against other JRPG characters (a Tales rep), while Banjo hurts the chances of other platformer characters (like Crash). When you put this together with other stuff like the companies already involved in Smash... here are a few thoughts.
Bandai Namco: From the beginning, Bamco was one of the best candidates for DLC imo. It's so strange that they're helping make the Ultimate Smash Bros., yet only have one character of theirs in it.
As I've said above, I think Tales might have been hurt by two JRPG characters already in the pass. If we're going by presence in Smash 4 this makes Tekken the prime candidate as a series to get a new character. Specifically Heihachi, whom Sakurai flat out said he went for during Smash 4, but had trouble implementing. He would fit the theme of being "impossible" due to technical stuff, ironically.
There are other contenders, however. Soul Calibur is still a big deal and Dark Souls is kind of an exception to that thig with JRPGs because its demographic is vastly different. And this is only from the "Namco" side of things. I think Digimon should not be underestimated as a Bandai rep. And yes, even though most games are RPGs, there are other sources to pull from with Digimon, so it's another exception.
Capcom: Two characters already in Smash or not (three with Ken), it can't be denied that Capcom's huge amount of content in Ultimate means they are really keen on supporting it. And they are in advantage when it comes to having a library full of beloved, recognizable characters.
With Monster Hunter already having base game content and Dante deconfirmed, I think the most likely DLC could come from either Resident Evil or Ace Attorney, both of which kind of represent two new genres (in DLC) at once (respectively, Horror & Action/Shooter and Adventure/Visual Novel). They could also go with a "weirder" pick, like Viewtiful Joe, Amaterasu or Arthur, though I think these are slightly less likely.
Koei Tecmo: Though they technically already have content in Smash in the form of Fatal Frame, Tecmo is one of the only two companies that have content in Ultimate, but not a playable character (the other being Ubisoft).
The character most people talk about is Ryu Hayabusa. With Dragon Quest being in, Ninja Gaiden is arguably the last remaining NES-era icon not already in Smash. Personally, I don't know the possibility of other Tecmo characters, as all speculation seems to center around Hayabusa. The only thing in his way is the fact that he's... well, a retro character. I don't know how willing Nintendo will be to pursue another one after Banjo.
Ubisoft: With the floodgates for western characters now open and Ubi already having Rayman and some Rabbids as spirits, they would be in prime position for a character. Problem is... they honestly don't have many franchises that are big in Japan and I have no idea if Nintendo would allow another western-centric character for DLC after Banjo. That doesn't mean it's impossible, though.
The ones people seem to talk about are an Assassin's Creed character (Ezio is usually the one talked about) or a Rabbid. I think both could please different segments of an audience that normally doesn't care for Smash, with AC appealing to core gamers outside of Smash and the Rabbids appealing to the casual masses. It could go either way, really.
Bethesda: While they don't have content in Smash, Bethesda seems to be giving a good amount of support to the Switch. Sakurai also seems to be a Fallout fan and we all know that Sakurai liking things can go a long way sometimes.
Doom Slayer/Guy/Marine seems to get the most attention, especially because it would be a western Shooter rep, but Elder Scrolls and Fallout could also bring that Western RPG charm with them, who knows?
SNK: Seriously, why are you guys sleeping on SNK? They might have lost power compared to the arcade era, but their games are still nothing to scoff at. Along with Level-5, they're the last notable japanese company without any sort of content in Ultimate.
The most obvious rep would be Terry, representing both Fatal Fury and KOF, in a way. There's also Samurai Shodown to take into account. All in all, when it comes to fighting game characters, SNK is toe to toe with Bamco regarding Smash DLC.
Level-5: Level-5 has been a good partner with Nintendo for the last few years. While I think a Yo-Kai watch character was hurt by the presence of Joker and Erdrick, there's still Professor Layton. If SNK characters go toe to toe with Tekken and Soul Calibur, Layton does the same for Ace Attorney and should not be underestimated for his genre and the appeal of his series with a more casual audience.
...God, that was a huge post. Sorry, took a while to gather my thoughts about everything, but this is the current state of the FP imo.