Cawthon launched a teaser on his website Scott Games to show off an eerie image of an animatronic with the headline "SISTER LOCATION" underneath the series title. The tagline "There was never just one." Information for what this teaser could entail are scarce, but the mentioning of location could mean that the next game in the series could be set in a new location altogether. It could potentially go on to explain the origins of certain story elements seen in Five Nights At Freddy's 3, or the origins of the animatronics.
Five Nights At Freddy's has been met with criticism for its frequent sequel releases and simple jump-scare tactics to terrorize players, but overall, the series has been surprisingly successful and Cawthon clearly does not want to let that success and fan base go to waste.
While no details have been revealed for Sister Location, we'll keep you updated on information that does emerge.
[Source]