The Steins;Gate comparison doesn't really work, because a different world line implies there was a massive change that altered the course of history, which is the exact opposite of what SoulCalibur VI is doing. It's filling in gaps and expanding on stories, but changing nothing of importance. It would only work if Azwel and Grøh were important outside of Libra of Soul, which is non-canon. Or we could maybe say that Libra of Soul is a different world line, I'd agree to that, but because it's non-canon, there's no "new timeline" for the main series, unless we're also saying Chronicles of the Sword counts.
Adding more fuel to the Lizardman is in the game fire, condolences to Korean swordsmen.

You couldn't use Ezio or Algol for CaS in SoulCalibur V either, oh wait...


Kinda yeah, more or less, but also... too many signs point to Lizardman being in that I have to feel inclined to believe, and he would make sense next to Creation, while Edge Master would make sense next to Random, but this line of thinking means no Hwang without DLC, and I don't like his odds there...
You'll continue being one step behind, because this infographic also doesn't mention the new weapon that was just seen a little bit before this post that I quoted above by T.Rex. But the real mysteries are never solved, so you'll always have work, I'd say.
If they were able to de-clone Mi-na, then they should also be able to de-clone Cassandra and Amy, if you even believe them to be clones to begin with.
It's legitimately impossible to please everyone with the limited number of slots. Even if we do get Cassandra and Amy as DLC, we're still not getting any vibes that seem like Hwang or Yun-seong are going to make it in either form, which is a real bummer. We'll just have to take what we can get, and hope for this game's success, so that SoulCalibur VII may actually have the perfect roster.
I know this was answered already, but it would be really dumb if we couldn't, but we also had Dampierre as precedent for saying that it's going to be possible, and in that Geralt is usable, it's very possible that the second guest, if we do get one, would even be usable as well.
Honestly, I think the 1060 would be fine for SoulCalibur VI, but it depends on what else you're planning on playing, whether or not the upgrade would be worth doing. 1060 to 1070 Ti would be a step up, and 1080 Ti would be a couple steps up, but when you're already above goal, you're mostly just getting bonus points if you could already run the game maxed out as it were. I'd only upgrade in your case if you wanted to play the game in 4K, if you were fine with 1080p, the 1060 should be more than capable of getting the job done.
So essentially, a bunch of idiots ruin it for the creatives who would actually use the system to make interesting designs. CaS isn't the problem, people are.