It's a catch 22. My first and only trip to SeaWorld is actually what really turned me against animals in captivity, especially against animals performing in captivity. I guess it's partially because the shows felt so unnatural, but something clicked inside of me, and I began to very much dislike what SeaWorld (the park) was doing. SeaWorld helped my appreciation and love of animals to grow. They taught me by being the bad example. If I hadn't been disturbed by SeaWorld, you would not be reading this point.
I'd be almost content if all capturing and killing of endangered animals were to stop completely. SeaWorld isn't doing much direct harm to wildlife right now, since I believe they no longer take animals (endangered ones, at least) from the ocean. But how do you stop hunting/capturing of these animals in other countries? SeaWorld-esque parks show no signs of decline in China, and neither do their harmful means of getting animals. I think, if SeaWorld were to successfully change their business model, they could become the leader, the example for parks all the way down to zoos and aquariums and even pet owners around the world. It's like when one country would get rid of slavery... eventually the neighboring ones would follow by example, and in the long run, equality would be (perhaps will someday be) fully reached.
And you make a good point, if every zoo, aquarium, marine park, etc. closed, where would people learn to appreciate wildlife? I think Rivers of Light is a step in the right direction in this regard. Treks through very "natural" places like Africa, while not as accessible, are typically far more powerful experiences than zoos. Videos and shows of such places are also good. And I don't believe that some very high appreciation for wildlife is being exhibited today, to begin with. But I do agree that at least some educational value may be lost.
It's a tricky message when you're holding certain animals in captivity and making money off of their lives, but using part of that money to help other animals. I may be totally off on how things should play out. But in the end, I'm a bigger fan of leading by good example rather than by bad example. I admit that I don't have a solid idea of how that conversion should happen, but I like to at least see progress.
That's my logic. Hope it makes a bit of sense.