These seem like the most realistic options, but I'd add one more:
Group E) Namco has lost all marketing sense and one of the DLC characters is Edge Master. The reason why I'd add this as option is because Edge Master is listed as a selectable character and fighting style in the game code. But maybe he's a character they were considering to add but they changed their mind, or maybe his name was used as a sneaky placeholder for 2B.
Overall, I'd say B, C, and D (D probably being Setsuka and Hilde) are the most likely options. I don't think A is very likely (I think they planned Lizardman to be AI-only from the start).
And after the reveal of 2B (like most people, I didn't expect the first character reveal to be a guest), I think the possibility of group B is pretty strong. I don't like the idea of a season pass filled only with guest characters, but as long as Namco can make those deals, then it seems like a good business decision. I'm seeing a ton of people saying they're interested in SC6 only because 2B has been added to it and the 2B character trailer is the trailer with the most views on it. I don't think any returning character announcement could garner this kind of excitement.
Anyway, I hope it doesn't take too long before the other characters are revealed. It looks like 2B started development around January, and if that's the case, then I think it's very possible we don't have to wait a long time for the other DLC characters. I think it's realistic they would have had the time to finish up most of the work on 3 DLC characters since January.
One last thing to add, in this interview Okubo said the season pass could include a returning character from IV or V:
http://kayane.fr/2018/08/23/kayane-...h-motohiro-okubo-producer-on-soul-calibur-vi/
Okubo has been surprisingly willing to throw out hints in interviews, so this could be a strong hint we'll be getting characters 4 and/or 5 in the season pass. If it's from 4, then it's Hilde or Amy (though I'm not sure if Namco sees SC3 or SC4 as the proper introduction of Amy). I have a hard time seeing them add anyone from SC5, but if they're doing that, then surely it's ZWEI or Viola.