With regards to the DLC of the second season pass, they can afford to be a little more free about what would or wouldn't sell if what
@Sectus surmised is true, and the characters will be released in pairs.
Stone and Yell, if that's Rock and Li Long, will definitely mostly just be for old schoolers who know who they are and/or care about them. It's possible that Rock might could end up with something derived from Aeon's style from SoulCalibur V, since dual axes could definitely be a Native American vibe, and would set him apart from Astaroth in that way. It also works out to go with Li Long if he keeps his dual nunchaku style from SoulCalibur III, and thus this pair would be both dual-wielders and classic characters. If, for some reason, Yell is Hilde instead of Li Long, then I guess she becomes the selling point of this duo, and she also is using two weapons, though they are different, not a pair of them.
Star and Snow, if that's Yun-seong and Setsuka, will definitely appeal to a lot of folks, being two unique styles that aren't present in SoulCalibur VI. These characters are also both tertiary characters that don't really have a story of their own, but are linked to another, in Hwang/Seong Mi-na for Yun-seong and Mitsurugi for Setsuka, so there's another theme at work. Not really much to say about these two, they're both requested and unique. This is definitely an easier sell, which leads me to the last pair...
Reptile and Yellow, if that's Aeon and Hwang, will definitely get the Tira reaction, I think, in that it's pretty obvious that both of these characters were meant to be included in the base game, but weren't, for whatever reason. Unlike Tira, though, these two don't actually appear in combat, save for the one fight in Libra of Soul where you fight the Schwarzstrom, and technically Aeon among them, but he has nothing to distinguish him from the rest of the Lizardmen you fight in various other places. Hwang, though, is in both story modes and weirdly never fights. Still, there is definitely demand for these two, especially Aeon, for those who are left wanting a lot more from creation mode Lizardmen, who are really lacking compared to other races.
I thought I heard Amy was in March, hope I'm right but I won't hold my breath. In any case, I expect the S2 announcement at EVO.
The only thing that ever said Amy was in March was a post like ten or more pages ago in this thread that didn't cite a source or back up the claim whatsoever. All we have is "soon", and 2B was "soon" a month and a half before she came out, so April seems pretty likely. And if Amy is in April, it would then follow that the next CaS pack would be in June, and then Cassandra in August. We already have the two months window as a pattern, but Amy coming in April would solidify it that much more for the last two releases for the first season pass.