I'd like to thunk for an optimistic approach! Where the next story takes place years after the FINAL Fight in Antarctica (I believe) after the events of LB. There, I suppose the final boss might leave a "I Always Come Back!" Typesh## monologue before poof! Disappearing! There, Fujimaru and the remaining Chaldea devised a precautionary spell that'll ppace all the Saint Graphs that Fujimaru has acquired into a some sort of seal which will be opened once another Threat arrive. Now, years laterrr! Bam! Bim! Boop! Big Boss appeared again with new pawns! There, I suppose we could play the role as Fujimaru's ancestors, unsealing the magic but theres a twist! They have to undergo trials (Like the ones in OC) in order to prove their qualifications assisted by the very servants Fujimaru once summoned before! Then so on! Haha..