Are there any popular theories out there yet?
Nothing super revealing. Some viewers wonder if the references to Butte at the end of Cult hint at a trip to Montana next season -- perhaps to tackle the city's early mining days. Some believe Cult's regal references and repeated use of the word "revolution" could be a sign the show is jumping back in time to the American Revolution. And others have been revisiting the popular Inferno theory, which Murphy teased before Cult premiered, for clues. (See above and here.)
First popularized by TV site Red Herry, the Inferno theory angles "each season of American Horror Story as a 21st-century interpretation of a circle of Hell" -- referenced in the first part of Dante Alighieri's 14th-century epic poem, Divine Comedy. Murphy has yet to officially confirm the theory, but he does like it! If it's legit, it could hold major clues about the crimes, punishments, big bads, or themes to come (see: Lust, Violence).