Michael may be the Alpha and the Supreme
When probed by the Hawthorne warlocks, Cordelia reveals that her greatest fault as Supreme was her inability to save Queenie from the Hotel Cortez, where she died. Despite her best efforts, Cordelia couldn't help Queenie escape from the hotel's purgatory, and so she was trapped there forever. But Michael, overhearing this, sets out to do what Cordelia could not. He travels to the hotel and effortlessly gets Queenie out of its clutches. The two also make a pit stop in Madison's personal hell, where she was trapped after her death at the end of Coven. With the two irretrievable witches retrieved, Michael heads back to Hawthorne and intervenes Cordelia's departure. She faints at the sight of the girls she couldn't save.
Michael's abilities are stronger than any we've seen before, unparalleled even by Cordelia or her Supreme mother, Fiona (Jessica Lange). The audience is aware that Michael is the Antichrist -- as warned in Murder House, the Antichrist would be born of ghost and mortal, which Michael was -- but the witches and warlocks aren't. To them, Michael is the fulfillment of the Alpha prophecy. But if the Alpha supersedes the Supreme, rendering her role moot, wouldn't that make him both the Alpha and the Supreme?
Or maybe his role as Antichrist is something else entirely. Maybe he isn't the Alpha or the Supreme, and is instead an almighty force neither can touch. His powers may look like that of a warlock, but as one of the council members, John Henry Moore (Jackson), points out, Michael's magic feels "different" and "darker." The ability to raise souls from Hell is a magic witches and warlock are not known to possess.
If Michael's Antichrist magic puts him in a league of his own, who could possibly stop him? We're guessing the witches and warlocks team up to take Michael down, but even they might not be powerful enough to overthrow the Antichrist. If they can't do it, who possibly can? There's another nugget of information in Episode 4 that might hold the answer to that question.