While I never got to experience Trick or Treat: Lights Out, it honestly looked really cool and creepy. Plus, I find the flashlight gimmick way more intriguing than a lazer gun, especially since the flashlights aid in ratcheting tension and providing scares. Where as the guns, you're more focused on shooting things and you can honestly miss a lot in the action.
And I think the Zoo is a great theme to bring the lights out/flashlight gimmick back. Anything abandoned (such as a zoo), or a facility where things have gone horribly wrong (such as the military base/lab in said zoo!) is pretty fitting. Especially when you're dealing with human animal hybrids who can probably see in the dark very well.
I too, am very curious to see how ops shakes out with the changeover. But I think a factor of them doing it this way is because it'll allow us to see what the house looks like normally beforehand, and then we'll see the sinister juxtaposition of going through it in the dark. Meanwhile Trick or Treat was lit up for years before going dark, so most folks could remember what it was before the notable change.