Now that we know William took ownership of Edwin’s land, it’s theorised that the house eventually became the Afton home after it burned down, mainly due to its similarities to the FNaF 4 bedroom. If that’s true then the Sister Location facility would likely be beneath it, which is something we have theorised about since the breaker room map. Even the ending of Ruin seems to support the idea that the Sister Location bunker is located there.
A perfect setup for this sequel game could follow a protagonist investigating the fire at Murray’s Costume Manor and Edwin’s property years after Secret of the Mimic in 1979. They could even be sent undercover as there are suspicions surrounding what Afton is doing after acquiring the property.
We discover an early version of what later becomes CBEAR underground, along with prototype versions of the Funtimes. Circus Baby herself could appear in a much earlier form and resembles Scrap Baby more closely than her later design. That could finally explain why she looks so different in Pizzeria Simulator. After separating from Ennard, she had to resort to reusing an older body, one that William originally built while still developing Baby, using parts of Edwin and Fiona’s characters including Party Time Chica, the roller skates are 1:1 with what we see in Scrap Baby’s design. Also I could see him taking ‘Party Time’ and branding his own animatronics as the Funtimes, It would fit his character perfectly as he would just reheat their nachos, as he likes to do.
I think a game like this could finally give us more answers about why William created Afton Robotics, LLC in the first place. Thank you for reading :)