To the poster who mentioned it not fitting on the CC standard, my impression was that it was a corner with the first connection point on the back (away from the photo we saw) and the second in the fence on the left. Pure speculation there, though.
I don't think it'll be a modular, but I do think it'll be modular scale. Lego have been very smart recently - even their friends, city and creator sets are starting to have 'modular' elements, letting you remove floors and/or rearrange them in different layouts. So fingers crossed they realise that some will buy the haunted house to go in a modular town so the scale will need to work.
I think it'll work better standalone anyway, its the perfect 'that scary house that the crazy old woman who might be a witch lives in' that many of us had in our towns and our imaginations exaggerated as kids.