We know that Scáthach utilized the powers of gods more ancient than christianity. We also know she was the first supreme and started the transition of power through the Witch Covens we know from the show. It is no surprise to me then that witches would be powerful enough to handle the antichrist…considering their dealings with the old gods. That is also assuming they aren’t intending to help him.
Either way they’ll require powerful members…perhaps we’ll see Queenie, Misty Day and Myrtle return as they are summoned to use their forces in the apocalypse that is to come.