Final chapter of the Lostbelt Arc, what will happen?

The FGO final chapter of the Lostbelt Arc is really amazing. Just going through the story, revelations after revelations, surprise after surprise. I hate Marisbury for what he did to the poor Olga Marie, but I don't really know how they're going to continue from here.
Victory means disappearing as the FGO timeline is a lostbelt by itself, how will the story end tomorrow? What will part 3 be about considering the game can't end yet? Will they change protagonist or...