Do not under-estimate a Disney Store employee.
I have a family member that is asst. manager there. Granted they do not know everything but generally they won't tell you something unless its a confirmed fact. They have newsletters that go to each store every month or so and they are a huge network. Of course this doesn't mean it's a 100% fact its being released but its a good chance.
Another good way to find stuff is to search the net for future Disney releases and always check back with their site. I've found info about stuff 2-3 years before release on the net and Disney tends to update things as soon as they can so they can push merchandise.
Also, when Disney re-releases movies they tend to pack on the extra features in order to push sales. Kind of like Pirates of the Carr. They released it with an extra disc. Or Princess Diaries was also released with extra bonus items when they released the second movie to theaters.
I was just watching Muppets Take Manhatten with the interviews with Jim Henson and I was like man I wish there was more of this kind of stuff.
Just a little hope sent your way!