I think CaoCao was saying that the recent Injustice/MK games have too many guest characters for his taste and that he would rather SCVI didn't fololow suit, rather than that he expected MK/Injustice characters as SCVI guests--which i believe would be incredibly unlikely in any event.Same for MK Injustice and DMC, however Samurai Shodown, FF and Sekiro I'm Fine...
Personally, I am agnostic on the guest character issue. I really don't mind them where they are handled with care and in a manner that preserves their visual aesthetic and fighting style in a manner that is both faithful to the character and works within SC's systems. When done right, some characters can add great new dynamics and textures to the gameplay that keep things fresh. And that is something that Project Soul have traditionally excelled at: choosing the guests carefully for those needs and then translating them with attention to detail. More nerdy concerns, such as story continuity issues, are of no moment to me. Additionally such characters can bring in new players, extending the profitability of the game and continuing DLC support. However, there is the factor that every guest is likely to supplant a regular roster character--this is not always the case, as a developer may take the approach that a guest character will "pay for themselves" in terms of DLC sales (or extra sales of the base product if they are included in it) and may therefore plan accordingly in a way that they are added on to characters already planned. But in the long run, at least some guests will replace franchise legacy characters and new ones.
In the present case, whatever I might want, I don't think we should expect a guest in Season 2: I'm fairly convinced at this point that the plan is to flesh out the entirety of the legacy cast from Soul Edge through Soul Calibur III (meaning Season 2's six characters will be Aeon/Lizardman, Hwang, Li-long, Rock, Setsuka and Yun-seong) and that there will simply not be room for a guest character. However, on the outside chance of a Season 3, I would not only expect a guest character, but also a new original character. A Season 3 with Hilde, Algol, a guest, and a new character would suit me fine--though push come to shove, I'd be happier with Viola than a new character, though I doubt she is planned, based on the importance PS have placed on narrative continuity in this game. Of course that projects a return to four characters for this hypothetical third season pass. That just seems more likely to me; a third season is very much a far outside possibility as is, and I can only presume if it happens that it will be smaller in character selection.
One open question for me, now that we are getting some vague hints that CaS train may not be done, is where that content will land and where we might get any extra stages, were that to (very hopefully) happen. All of that would fit better with the third season pass in terms of making each season or roughly equivalent value if Namco wants them to all share a similar price point (which they probably very much want). But I'm not sure there will be a market for them that long if they delay another year before introducing them, which is what will happen if the current pace of DLC drops continues. That pace is actually faster than the average for such games, and quicker than even an optimistic projections/guesswork from fans up until recently, but it's still going to take time before they announce a season three, in the unlikely event there is one. I'm not sure how deep the pool of potential buyers will be at that point. But I am interested as a fan of the series (and someone interested in where trends in continuing content support for games and fighters in particular) to see how those matters play out.