On Mouse|Tunes they talked about the Mermaid Lagoon coming to the 20,000 Leagues area. Lou said something about if they built the Mermaid Lagoon they would be removing Pooh's Playful Spot. That's not necessarily true. Pooh's Playful Spot would most likely stay there with Mermaid Lagoon built next to and behind it. PPS takes up very, very little space given how much area is actually there and it doesn't look like it would be removed for something like this. It is considered temporary but not to the point where they would remove it after a couple of years.
Personally, I would hate to see Mermaid Lagoon being placed in that area. That area is huge and has a ton of potential. It has enough room for an E-Ticket ride or a few dark rides. Mermaid Lagoon is nothing more than a glorified carnival. All the rides can be found in ANY theme park across the country. I'd be really disappointed if they wasted the space in this way.
The last I heard the Villains attraction was going to be a Bald Mountain attraction. That is purely a rumor though and doesn't look to be happening in the next 3 years or so.
They go on to talk about a "construction area" near Expedition: Everest. That area has been there since the park opened in 1998. It is nothing new and the last I heard construction isn't even planned to start it that area. I have heard a few things it COULD be, but at this time it's best to make your own guesses rather than starting up new rumors.
Just wanted to add on to what Mouse|Tunes has talked about.