Hasn't Slaythe already confirmed that he saw SSB Goku as a seperate character. Hopefully it isn't a problem for me to say it, as Slaythe seems to have stopped doing so.
Dragon Ball Super is the face of modern Dragon Ball. I don't see any way that Bandai Namco allows ArcSys to not include the DB Super characters that were at the height of their popularity as development would have been starting (i.e. Hit and Goku Black). Leaving them as DLC characters doesn't seem like it would make sense, as they would have known that Super was continuing and that new Super characters could be DLC.
DB Super characters were a major selling point of Xenoverse 2 (for pre-orders, the game itself and DLCs), garnering millions of video views when the inclusion of Super characters were announced. For Dragon Ball FighterZ to go through its entire marketing campaign without being able to tout having characters from Super seems like a really poor business decision.