I think splitting the story arcs could be a viable option, however just as locomotor79 and TheRealArma stated before me, not if it means we lose our previous progression state or access to previous scenes.
Viewing post in The Rhythm is Returning comments
Yes, I would think the majority of us consider the gallery an important part of the novel/game. I haven't done any coding for almost a decade, but I think you could perhaps internally link the gallery between the original and any additional arcs, although that would require keeping all previous content installed. For myself that wouldn't present a storage space problem, but I suppose there are others for whom it might.