I call "bogus" on this rumor for so many reasons.
First of all, why does anyone think this would improve the ending? Those AA's from MMR are about the size of an IASW doll and have almost as limited of movement. Besides having to squint to see them, it would be the most static, lifeless ending imaginable! At least the current set up is large, has lots of energetic movement, and dazzling colors.
Second, Disney is not going to just trash the thousands of dollars invested in the current ending. That rear projection screen and the digital projectior cost a bunch of money, not to mention what was spent animating that sequence of film.
Third, from a creative and historical perspective, the ending film is the one most inspired by "The Three Caballeros". Their choreography is almost identical to Walt's original movie. Again, you're not going to get that energy and flavor with some ancient AA's bolted to the floor.
Fourth, Disney is in the habit of removing AA's, not adding additional ones. Why would they spend money to install and constantly upkeep something that, quite frankly, better in it's current state?