From what I understand, Tarzan Rocks was closed because of the noise from Everest, and not just because they wanted to close it. It remains to be seen what will end up there, but if they enclose the theater I would imagine they would create a different show that makes more use of the dark settting.
I, for one, never get upset when a show that I have seen before closes. I've seen it, let's see something new. Yes it was good, but I am excited to see what new magic they can come up with. That's just me.
Just for the record. FLK is much, much better than Tarzan. Much better