Bryan, while there has been no official announcement of Disney's future plans for the old 20,000 Leagues area, I don't think they have abandoned their plans. You see, I think that the Pooh's Playful Spot is just a place-holder while the land settles, which could take years. It may not be a roller coaster necessarily, but I do believe it will be themed to the Disney villains. In the meantime, the Pooh meet-and-greet area fits right in Fantasyland with the adjacent Pooh attraction.
Our family is keeping their fingers crossed that the villains will get some recognition by the powers that be!