Don't worry, I'm pretty sure that we will get witches one day as they have been part of The Sims since the very first part. But I really hope that it's going to be a GP because in my eyes GPs are of a much higher quality than EPs.
But I want them to be a complete lifestate like vampires, not just a bunch of magical rituals every sim can learn. It's more fun to see how non-magical sims get sick over the smell of the strange substance in a witch's cauldron or how they get their hands jammed in the spellbook as it automatically closes when touched by a "muggle". Furthermore I want an own magical world / town, appropriate new lot types that wouldn't work without a lifestate and new ambitions. And I want magical sims to be customizable in CAS and also regarding their powers and weaknesses (like vampires).