Speculation, always speculation.
When it was announced in 2009 that Disney had purchased Marvel, many wondered if the mouse house would adapt any of the superhero stories into animated features. When the deal was announced, CEO Bob Iger mentioned that they “talked about this internally” and that Pixar head John Lasseter had already “talked to the Marvel guys” about possibilities ...
[quoting Blue Sky:] The projects competing for 2014/2015 are the uber-secret film from Don Hall, which will be a marvelously unexpected project if it ever gets the green light, and Nathan Greno and Byron Howard’s films which are deep in development. ...
There are multiple fairy tales in development at Diz, and a person told me that Hall is developing some action thingie. But tied to a Marvel property? If memory serves, no. (But maybe this is later news. I get around so little.)
I know the fan-person crowd is always chomping to know every little bit of news that comes out of Disney, but honest to God, it isn't that exciting.
The reason it's not? Because at any given point in time, directors and story artists are developing projects. And a lot of those projects never get past the early gestation stage. (King of the Elves has been up and down the May pole multiple times. Frozen has been in and out of work four or five years at least. It was killed as a hand-drawn project, then resurrected as a c.g. fairy tale after Tangled's success. Plus, J.L. liked one of Frozen's later scripts so it moved up in line.)
The way development of animated features works: Creators dream up multiple projects and storylines. Mr. Lasseter looks at same, selects one of the projects/storylines for further development, and off everyone goes. Writers come aboard, scripts are written, and table reads of those scripts (with Mr. Lasseter in attendance) take place. Then, if Mr. Lasseter's reaction is "thumbs up," further development happens (sequence boards, story reels, more character designs, etc.) And the reels either lead to a production greenlight or not.
Before that, most everything is a candidate for a quick death. (And possible later resurrection.)
None of the above is news. The process has been pretty much the same since Hyperion/Snow White days. One difference now is that outside writers get hired on for script work, which was mostly done with in-house staff prior to the middle 1980s.
If I were more energetic, I could probably nose around and find out who's doing what and which projects are "looking good" and which not. But it's not something that is, at the end of the day, all that interesting. Projects fall on and off the tote board all the freaking time. (Tangled was in development for over a decade, with all kinds of different approaches. The only one that actually counts, when all the storyboards and script drafts and box office grosses are tallied up, is the approach that gets made.)
Disney now has more projects in different phases of development than previously. This is a good thing. But many of the incubating features won't be made anytime soon because that's the nature of development work. There are always many ideas. But only so many features can get onto a release slate.