Yes, I am digging and looking for any information that will confirm exactly what this is.... a board game or a full on tabletop mini's game release. The latest information I have though is not yet definitive, and exactly as I get the info.... I will be on it and let you know what we are looking at.
Here are the latest rumors, these ones come from Dakka
BTW, my source "confirmed" it will be $149.99 USD (he is so certain he said if it is more, he will pay the difference for me. I have witnesses to his saying that, and I am holding him to it.)
From my source: This is a big release. GW reps are getting two days of training on the product line and rules, as they did with Age of Sigmar.
My opinion: This implies it will be the launch of a whole separate product line, and not just an accessory to 40k.