Selling out does the event no favors. I'll say it again, online fanbois with FFPs are not the bulk of the money for this event. The people paying $80 a night are the economic engine. Nobody paying that money wants to wait 2.5+ hours for an average house like TWD. Nobody paying that money wants to do only two houses in a night--especially without any scare zones to make up for it. I can only imagine guest satisfaction numbers must be horrible after that. (This is based on personal experience--when I lived in Daytona and was still ignorant of multi-day tickets, I skipped either 2003 or 2004 after paying full price to see only two houses the year before.)
Equally importantly to Universal, guests in line for 2.5 hours aren't buying a whole lot. If they carry cash--rarer and rarer every year--they might buy one overpriced beer or Powerade in line, but the $10 blinky cups? A round of shots? $25 T-shirts? Dinner? Nope. This is the whole reason Michael Eisner pioneered FastPass at Disney. Guests in line don't spend money; FastPass was (and still is) intended to let you spend that hour you would have stood in line for Space Mountain out in a gift shop or grabbing a burger, putting more cash in the Mouse's pocket.
I assume we're not calling the new scaractor troops "crap." So quality people are theoretically available, they found like 80 on the spot last week. With time, and admittedly resources, the design team is capable of creating more houses--I'm sure they have no shortage of ideas. And IoA has quite a few rides ready to go, a couple of which could be sold as a different experience after dark, much like Jaws was. Planned out from the beginning--and not thrown together because Publix sold too many tickets--I think a two-park event could be a quality experience that still manages to diffuse crowds somewhat.