We will have to agree to disagree, my friend. Magic Kingdom isn't called a Rivers of America Park or even a Tom Sawyers Island park. It is know and described as one of the many Castle Parks connected with Disney. How many people have gone to WDW and never even knew that Tom Sawyer Island and Rivers of America even existed. I've met many, they didn't expect it, they didn't think it was anymore than just the surrounding landscaping. Personally, in spite of my fandom for almost 40 years, I went there on my first visit, with my kids and haven't set foot on it since 1983. Apparently, didn't leave much of a need to experience it again. The Rivers were and still are an important part of the glorious landscaping that most Disney Parks are known for and expected to continue.
Remember that is not to say that removal of the previous two isn't just Effing awful and sounds like it was thought of by someone that, like the song in Chicago says... "With one more brain what a half wit they'd be". Yes, they are iconic, but are not the thing that stands out and is seen and expected by everyone even if they have never been to the place. I'm sure they have records telling them about the near revolution stirred up by just making it look like a Cake. That is why I say it isn't really comparable except that they are all In Magic Kingdom. If there is no other reason to know it isn't going anywhere is if you just think about how many Disney Movies would have to have the beginning altered if that isn't the main Disney Identification.
If, however, I am wrong and they ever did try to remove it, that would be a sure sign that WDW is on it's way out, at least of Florida.