Toy Story makes the most sense out of the Pixar worlds. I don't think there will be a Monsters University world, though it would be cool too. That movie's just too new to include it. I think Tangled and Toy Story are the most likely worlds from the Disney 3D animated universe.

I'd like to see some more classic worlds like The Jungle Book, The Sword in the Stone (Camelot would be an awesome world!), Robin Hood, The Rescuers, Pocahontas, and The Hunchback of Notre Dame.

And, obviously, a Wreck-it-Ralph world would be freaking amazing but fat chance of that one happening, unless they only use the Disney IP characters from it.

In my opinion the new worlds will be:

Toy Story
Tangled
The Jungle Book
Pocahontas
One more from a non-animated Disney property
A unique world to the KH universe (or two)