I wouldn't say that. A lot of people really like puppets, it's just difficult to find an audience for them, mainly because of the stigma that they're strictly for little kids . . . remember, Jim fought hard against this, and he actually succeeded to a degree: when TMS became a smash hit, all three of the major networks were kicking themselves for passing up on buying the show when he was selling it. Again, if Disney would just execute them better and stop trying to have them adhere to certain formulas that may work for other shows but not necessarily theirs, they'd probably do better.
It's not even a rumor, or even anything that's actually happening - it's all purely fan speculation and theorizing. Nothing more, nothing less.