Yeah, but don't be surprised if it's still only 3rd parties. Sakurai and Nintendo are pretty much going all out on getting licenses for many series and it's the best time to make this game as close to an official Mugen game before Smash gets that Reboot. The only 1st party series I can see getting a character is from Astral Chain for being entirely new and not having anything in Ultimate.
Sure but licensing and working with other companies can only go so far and get so expensive and complicated until it gets overwhelming. The bigger the roster and the more companies that work on the game the more bloated and complicated things get which is why I don't expect every single character to be from a new 3rd party franchise and company.
While I have nothing to back this up I get the feeling they wanted to blow through their big 3rd party additions (in terms of new 3rd party companies) in the Fighters Pass as we've only gotten 2/5 from companies already represented. Sure, I could obviously see more 3rd party companies jumping onto the Smash train but we don't know the limitations for the additional DLC characters nor the budget. It could be a complete reversal of the FP, It could be the exact same or it could be a mix of both 3rd party and 1st party (Which is what I think is going to happen).
And Sakurai himself said these additional DLC characters will have more of a focus on what people want so obviously we could get more 3rd party characters and franchises but there's a few 1st party fan-favorites/liked characters I could see getting added as well: Waluigi (If assists can be upgraded), Isaac (If Assists can be upgraded), Rex/Pyra, Geno (If you consider him 1st party), FE:TH rep, Astral Chain rep, Etc.
Maybe even Bandanna Dee and Dixie (if we get echoes) if they really want to pull a 50/50 split of 1st and 3rd party characters or even a focus on 1st party characters (Which I think is unlikely at best we'll get that mentioned 50/50 split or a 25/75 split)
And if it really is additional DLC like Smash 4 instead of yet another Pass I could really see us getting at least one if not three 1st party characters.