I think there is still a good deal o casting left to do. The skinny is that Lange, Basset, Bates, Lupone possibly Paulson are/were part of a single coven. Taissa and Emma will likely be part of a newer/younger coven. Although a standard coven has about 13 members, they don't all need to be main characters.
I'd love to see Evan be a member of Taissa's Coven.
Edit: I'm lighting my Alejandro candles in prayer that Kate Mara gets a starring role this season.
Also, I'm not here for historical figures as main characters. I like them as like guest characters like Black Dahlia in Murder House and Anne Frank in Asylum