Let's break these down. First, there's next summer's The Good Dinosaur directed up Up co-helmer Bob Peterson. This one takes place in a contemporary world like our own except for the fact that dinosaurs never went extinct. That's about all we know on the movie, aside from the fact that it's scheduled for May 30, 2014.
The other two do not yet have titles. One is directed by Monsters Inc. and Up co-director Pete Docter, and takes place almost exclusively inside the human mind. The next "delves into the vibrant holiday of Día de los Muertos," is from Lee Unkrich, who directed Toy Story 3. They're scheduled for June 19, 2015 and an unspecified date in 2016, respectively.
These three bits of art were revealed in a fold-out holiday card sent from Pixar to Coming Soon.
You can better dollars to donuts that all three of these films will arrive in 3D, so you'd do well to stock up on Rogue 3D Eyewear in advance.