Next Season on American Horror Story

Season 3 of American Horror Story is done and sadness ensues. But at least we can start speculating on what the next season will be about (at least until it's likely announced at PaleyFest in mid-March). So far creator Ryan Murphy has suggested the following:
It takes place in 1950 (and possibly set in the Santa Fe). Jessica Lange has a juicy part where she will speak German. Kathy Bates and Angela Bassett are expected to return. 
Internet speculation has been centered around a Circus theme, based on numerous fan art posters like those below. When Entertainment Weekly asked him directly about this he said:
"I saw those posters. I don’t know where people came up with that idea. Sometimes I think its people wanting us to do topics and doing fan posters. No one has completely guessed what it is."
TV also posted 5 Wild Theories about season 4 and included what I thought to be the ideal theme: Roswell. It wasn't until the Roswell UFO crash in 1947 (and the subsequent move to Area 51 in Nevada) that America's fascination with aliens took hold. With the McCarthy trials, The Second Red Scare and communism, the secret hydrogen bomb testing in the desert, and subsequent nuclear panic it sounds like a perfect season to me. (And what better place for an alien to hide than a circus?!?)

Aliens were included peripherally in season 2 but left rather open ended, and although Ryan Murphy has stated that he hates to repeat himself (ahem, Glee Season 2–5?) there's a much larger story to tell. We're all still obsessed with aliens, and McCarthyism, like the Salem witch trials, was one of America's greatest horror stories.