So far the roster of playable worlds is:
- Twilight Town/Mysterious Tower
- Hercules
- Toy Story
- Monster's Inc
- Tangled
- Frozen
- Pirates of the Caribbean at Worlds End
- Big Hero 6
Nomura confirmed Big Hero 6 will likely be shown next in a trailer so I'd expect that at Tokyo Game Show. Also given that it doesn't make sense to end the world reveals with one we've known about (BH6) and Nomura saying his favorite world hasn't been revealed I'm willing to bet there's gonna be one final Disney World revealed as well giving us 8 in total.
We've also seen some other worlds through cutscenes Land of Departure, Dark World, and Radiant Garden but have yet to see them in gameplay just yet.