Sounds cool, but I think it works better at Universal, although IoA does have some buildings that would be great for haunted houses already (dd castle). If they want to keep 5 like they have at Universal where would they be? I'm sure they will keep the same two soundstages between the parks. The DD castle will be used without a doubt, but where else? Screamscape said something about one in the Camp Jurassic section. It might work but it's outside, so it would probably close in the rain. That makes 4 haunted houses. The only other place I could see them putting one in is on the Dr. Doom line, but we will see, if this rumor is true.
I think they should include both parks in HHN. Think of all the Haunted Houses they could put in. If they make it big enough, you won't be able to see it all in one night, and would feel obligated to come back, which would be good for Universa.