Okay so random idea for a Dispatch/Fate franhise crossover:
Basically, post-Dispatch story, somehow a Holy Grail War is started in Torrance. Maybe the war in Fuyuki never happened, or maybe it's a stranged, borderline illegal war like Strang Fake. I imagine tha Malevola eould at least be able to identify that a Holy Grail is in Torrance, maybe also Coupe (via underworld connections) or Golem (I heard somewhere that he was created via magic). Regardless, the SDN ends up having to deal with mitigating a battle royale between servants and mages that aren't inclined to care about the safety of the populace.
The REAL thing that I think would be interesting, though, is if either MechaMan Prime or Astral were summoned as the Rider. So then Robert is forced to confront and fight his family legacy.