The Interlude is similar to the other flashbacks we get in the game:
- Episode 4's prologue with Maya, Josy camping.
- Episode 5's prologue with the formation of the DIK fraternity.
- Episode 6's prologue with Quinn, Rox and Buddy.
- Episode 7's prologue with Jill and Lana
- Episode 8's prologue with Bella and James
Each of these prologues provide past insight into different characters, particularly after a specific event involving those characters occurs near the close of the preceding episode.
The Interlude follows that pattern (given that one of the final scenes in episode 8 is Zoey returning to see the mc).
The difference of course is that we have some influence over Zoey's decisions during the extended prologue (and even her personality), and of course the Interlude is a lot longer than any of the previous prologues.
I do expect episode 9 to have an actual prologue, of Sage's past with the Burkes since that was the big reveal at the end of episode 8.
But I feel the Interlude is as integral to the overall story as each prologue so far has been. Meaning it's details of past events of characters that are important to the story.
If Zoey becomes a staple character for the remainder of the story, then the Interlude serves its purpose.
If Zoey ends up just having a cameo in Episode 9 only to fuck off for good afterwards, there's likely to be a riot. Both camps will be pissed. Camp Zoey will feel cheated, and Camp anti-Zoey will be able to proclaim that she was a total fucking waste of time.
Only time will tell.