There just doesn't seem to be a good answer to that question I'm afraid. If my recollection is correct, the Hammer was supposed to come out the "summer after SHOT" for three years now. Umarex isn't exactly broadcasting release dates, in part because they've been wrong so many times at this point. So I'm afraid the best answer I have for you is no answer.
What I can say though is, given the level of hype Umarex tries to build up around its products, I'd bet that when they're ACTUALLY ready to deliver the associated marketing campaign will be...... lets just politely call it "difficult to overlook."