I've thought similarly over the years: if the newer generations are never exposed to the classic Disney library of show, eventually, the market will dry up. So sad....
A few years ago, there had been a fan-produced site celebrating "Dr. Syn, Alias the Scarecrow." The site owner had lots of photos, history of the character, and audio clips. Additionally, he had a "news" page, and had claimed -- from an inside source -- that Disney had been restoring the show, but (if I'm recalling it correctly) they were having trouble locating a some original portion(s). This site was superb in content and quality. Then, one day, it was all gone!
Regarding "So Dear to My Heart," I don't understand why one of Walt's personal favorites has been release in England, but not here in a Region 1 format.... It's not like there are "translation" issues!
A couple of years ago, I called Disney Home Video, and asked about "Big Red." According to the phone operator, Disney had just recently regained rights to the film (perhaps from Anchor Bay?).
I certainly hope Disney isn't trying to capitalize on classic title demand by reserving their availability through the Movie Club only. I will say, that I've been able to purchase "Treasure of Matecumbe" (still sealed) and "Robin Hood" through eBay. Beside the fact that there are no extra features, there are no subtitles available. Now, maybe some of the other DVD titles do have subtitles -- I don't know. They certainly would come in handy for "Kidnapped," what with all of the Scottish dialect and historical references that are hard to follow. I've got a VHS tape of "Kidnapped," and found it hard to follow. I watched it multiple times, and really found it enjoyable.