I think you're talking about the FFVII remaster.All I want is some Final Fantasy rep in Soul Calibur. The weapon based fighting as well as the plethora of weapons for each Final Fantasy character makes it a good candidate game. It'd be a shame to see Noctis recycled. I'm trying to consider what is relevant aside from FFXV, though. There's a re-release of FFXII on the horizon, right? It would kinda tie in with the "reboot" theme to have a pseudo-throwback as a guest character.
Semi related, perhaps the "collaborations" could also include costume pieces to create guest characters.