Skull Kingdom seems to have closed more due to insufficient budgeting, poor location where the entrance was difficult to find, and later being bought out by a foreign investor who didn't even know what Halloween was, let alone try to run a haunt:
I do see your points. I selfishly would love to see a year round haunt, and TWD, love it or hate it, is a unique one of a kind attraction, even more so in a major theme park. But I totally agree with you for the typical GP, it does fall either into the "too scary" (especially for little kids--but I see LOTS of people come out of there absolutely terrified) or not scary enough. I can totally see how it'd be the lowest rated attraction. And as you mention, probably relatively expensive to operate... live actors aren't cheap.
I won't be surprised if it goes. At the same time, I can't see them closing it until there's something to replace it... and I think that's the bigger question: what can you put in there? I know some have mentioned making it an event space, but is it really big enough for that? It's unclear to me how much space really is in there. And there's already more than enough retail in the area. So what's left to do with it?