Here's my main concern with DA being open during HHN, what happens to all the day guests? I mean, if HE and EFG are sitting at 90 minute lines at 5pm, what do you do with the people waiting in said lines who have not paid for HHN entry? I do not really think you can open that area to HHN guest until the regular day guests are cleared out. Add to that the fact that you have to get the day guests out of the park in time for HHN and somehow be able to distinguish between HHN guests and day guests and you have what could be an operational nightmare.
None of this is even taking into consideration whether or not to keep all the stores, shows, dining establishments, and general walking spaces open during HHN.
My guess is they will take a year or two to figure this all out and then we might see DA open during HHN. That being said, I do not expect any houses, scarezones, or even scary music to be playing if they keep DA open during HHN.