Quick DLC wishlist/predictions. I'm unsure on the release schedule so I won't bother too much on that:
Nia: Rex and Pyra deconfirmed. Zeke and Tora possibly deconfirmed depending on how you view Spirits (I'm taking them as deconfirmed). That leaves only Nia and Mórag as the possible candidates from the base game XC2 Drivers. I would like either honestly, but Nia is my preference. Before, although I wanted her, I mostly just memed about her getting in over Rex to troll r/XenoobladeChronicles, but now I seriously believe she has at least a small chance. She's my favourite character in Xenoblade overall and not only that, I actually think she perfectly represents the series. She's got the surface level charm that drew Smash fans to Shulk, she's by far the deepest character in terms of development and backstory in XC2 IMO, and to top it all off, she could bring a ton to the table as a fighter. I envision her as a weaker but fast character, but she makes up for it with healing properties and some situational stronger attacks if she builds up Blade Affinity with Dromarch. They could also incorporate *SPOILER* if they want to, giving her a transformation property (or just make it her Final Smash). I reckon she'd be the first or second DLC character.
Sora: As far as big-hitting third parties that are left, Sora is the cream of the crop. KH3 is even more hyped than Smash Ultimate is and is overall a bigger game. He also has endless moveset potential. Personally, he's one of my favourite video game characters and it would be great to have any KH music in Smash (Yoko Shimomura already has songs in Smash so I don't think it'd be as difficult as the rights for FF songs). As far as a big hitter goes, I think no character is bigger than him right now, without going into Sony/Microsoft/non-video game territory. I reckon he'd also be first or second.
Rayman: Not as big hitting as Sora, but since he hasn't shown up at all yet despite having trophy presence in the last game, and he is a popular request within the Smash fandom, I think he makes a lot of sense, especially with Nintendo's relationship with Ubisoft. Rabbid Peach is also in the game as a Spirit so the Ubisoft presence is there. Once again, plenty of moveset potential, and he's one of my favourite mascot characters.
Fire Emblem rep: Controversial pick, but I think it makes sense. A new game is on the horizon, and we all know Smash's history with adding fresh out the gate FE characters, so a character from Three Houses could happen. They also have plenty of data to work with from the FE Heroes CYL events if they wanna put in an old fan favourite too. Out of the viable choices, Veronica from FE Heroes would be my choice, as she could have a moveset centered around summoning lesser FE characters.
For my last prediction, it's Dr. Eggman or a Gen 8 Pokémon. With Shadow deconfirmed, I feel like it's criminal that Sonic is the only ten year, perfect attendance third party character, and has had a consistent working relationship with Nintendo, such as the Mario & Sonic Olympics and the Yoshi and Zelda levels in Sonic Lost World - and he STILL hasn't got a friend/enemy of his on the roster, while Ryu only had to wait one game and Simon got one out the gate. And since we could use more villains, Dr. Eggman is perfect. I don't believe he's been seen as a Spirit either. I'm a huge Sonic fan and Eggman is one of the best villains in gaming, so he feels like a no-brainer to me.
As for a Gen 8 Pokémon, I simply think this might happen as a shameless plug for Gen 8, and if so, they'd be the last DLC character in early 2020 or something.