This is very exciting news! So glad to see Soul Calibur return in this generation!
Now for some speculation...
Just looking at them in comparison, the SCVI designs for Sophitia and Mitsurugi are definitely taken from the first Soul Calibur. So it could indeed be a reboot or a prequel of sorts, though not sure if calling it Soul Calibur 6 would be fitting then. I mean, yeah, sure, it’s the 6th in the franchise (well, 7th if you count Soul Edge/Blade), but if they choose to go back in the story, it’d be appropriate to have something indicating that in the title.
And if they do that, then I guess there’s not a lot of hope for Zwei and Viola to return. I grew to love them a lot in SCV, but they were newcomers to that game.
I do hope to see Ivy, Taki and Kilik though. ♥
Also, look at this beautiful official artwork: