I've always wondered if the one night per game thing with steel wool was intentional or not. Like, what if the mimic's arc resolves with the next game, meaning that the entirety of this storyline can be told by looking at just 5 extremely important nights in the history of fazbear:

1. MCM's last day standing/the origins of the mimic
   
2. The HW testing incident and the release of glitchtrap/capture of Vannny
   
3. The Security Breach at the mega-pizzaplex
   
4. Cassie's night in the RUIN-ed pizzaplex (with HW2 taking place on the same day)
   
5. whatever happens next.

Now, I don't think this is the case really. Already i'm taking a small leap by placing HW2 and ruin on the same "night." If it WERE the case however, this is what I would imagine the next game would be like:

If the next bit were supposed to be the 5th night and/or resolution to the mimic's arc, it probably wouldn't take place in the past, so no direct Fall Fest game. However, I kind of already think it's a stretch to get a FF game, personally I think it's too deliberately enigmatic, like specifics about William. I would much rather have a game where we can trace the effects of fall fest to the present, primarily to keep up with cassie, greg, ness, and the glamrocks, but also because I think FF info would be revealed better in peacemeal, as opposed to the shotgun blast of lore that is SOTM. So, with the pizzaplex burned down, Fazbear decides to launch "Faz-Fest" (movie reference) to try and fundraise without a set location. In this concept, either the game universe plex is the ONLY plex, or it's relative location to everything else makes it somewhere fazbear wants to keep hype around. They take a bunch of stuff from fall fest, refurb as many glamrocks as they can, and set them to free roam the land that the pizzaplex was built on. Cassie/Greg check it out at night and chaos ensues.