As much as I love Disney, and would love them to put more emphasis on TLK, it's still a business. They have to do what's going to work in their favor, and even with all of the TLK fans out there, that's not going to be the case here. They find something that works and use it as long as they can. For instance, the Hannah Montana, fairies, pirates and princesses lines. That's what they're making money on at the moment, so that's what their focus will be. If something comes along in the future, or if TLK somehow becomes big with the general public again, they'll move on to that. That's just how a business such as this works. It's kind of like the Twilight and vampires thing right now. Notice how EVERY studio is releasing vampire films right now? Even TV. And yes, Disney has one in the works too. It's what the masses want at the moment, so they give them what they want. (I've loved vampires forever, so this is awesome for me
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The new head of Disney animation is a big TLK fan, he's said so many times, but that still doesn't mean he's going to use it at this time. Walt Disney even said he liked his studio to "keep moving forward". And Lasseter really doesn't like sequels. He was even hesitant to do Toy Story 2, but the story was good enough that he let it go forward.
I for one would honestly be happy if they never made another film, but instead just re-release the film for new generations to experience. I was not a fan of SP and I was saddened by how much I actually disliked it. I don't want to go through that again. The first one is enough for me.
Oh and as awesome as a lot of the fanfic in this fandom is, Disney actually can't use any outside submissions like that. It's a legal thing.