A new character is only likely if they cannot get a guest to headline the season pass. The effort spent on a brand new character and a guest character is about the same.
Or if anything, slightly lessened in the case of the guest character, since they do not need to devlope the moveset, model, or general design from the ground-up, but rather start with a bit of a template in the form of the game or other piece of media the character comes from. Of course, that's if we're speaking strictly in terms of development team manpower: obviously licensing a character requires lawyer work-hours, which do not come cheap--but that's just one more reason why guests always require a certain threshold of unit-moving, mass-market appeal: they have to be worth the trouble.
Anyway, I agree a new character is much less probable than a guest. Just as I predicted parity between the 1st and 2nd season passes almost a year ago, I predict parity again between those first two seasons and the third: there will probably be three classic era characters, plus a guest to anchor sales on and draw in new players, and a roughly equal amount of CaS and secondary content. This is the simplest way to market your content, especially if you are in the middle of trying to sell your consumer base on continuing support release models, a strategy Namco are clearly doubling down on now: you want to five your consumer a roughly equivalent amount and value of content. It also allows the company (that is, the publishing parent company in this case) to projects rough costs and revenues.
Four slots would allow them to do with the third season what they did with the first and apparently the second: three classic era characters and a guest. Indeed, three extra classic slots would allow them to fill out the entirety of the classic era playable main rosters, plus have that important guest to help namco feel confident the third season will not fall off too much in sales compared to the first two. I could also see them maybe doing Hilde in place of a fourth guest. I think it's not super likely, but I do think it's a real possibility. Still, if I were a betting man (actually, I am a betting man, but not on the stakes I could drum up for this bet!), I would say by far the most likely outcome for the remaining content will be:
Season 2: Hwang, Haohmaru, Setsuka, Rock, and
Season 3: Guest #4 (/outside chance Hilde), Lizardman/Aeon, Li Long, and Yun-seong.
For obvious reasons, I am a little more confident with regard to Season 2 than Season 3, but if I had to make a guess, those would be my projections for the remaining continuing support on the game: and yes, I do think a third season is more probable than not.
That doesn’t say that Hilde literally took up the sword (and lance) and resisted the invading forces herself, but she commanded her kingdom’s troops and allied forces to do so. She doesn’t leave the kingdom until Algol comes forth, so I don’t think she would join the battle before SoulCalibur VII.
On the other hand, other characters have entered into the forefront of the retold narrative as playable characters earlier than they did in the original telling: Tira, Amy, Zasalamel. It's just while those characters all originated as playable entities in SCIII, whereas Hilde came in SCIV. Is that a distinction significant enough that the devs are truly unlikely to introduce Hilde in SCVI? It's pretty hard to judge on current evidence. I would say I lean slightly on the side of assuming she will not appear in Season 3 and that the next we will see of her is SCVII. But I go back and forth on it. It's currently the closest call of all the legacy characters, imo: when I look at any of the remaining main roster characters of previous games, I mostly feel like I can sort them easily into "more likely than not" and "likely not", and Hilde is really the only character who hovers near the middle. I do think she is drastically more likely than a new original character as DLC (though also less likely than a fourth guest).
