There are too many sequences that rely heavily on action to ever make it stage-able. Sure, some moments would be doable, and probably very magical, but it wouldn't work as a whole.
And while the story of Rapunzel is in the public domain, the characters in the film as well as it's plot complications and twists are owned by Disney...and the truth of the matter is, since all Disney really kept was "Girl in tower with long hair, witch owns her" and the tears at the ending, it was all the original invention of Disney (much like the talking sidekicks in Mermaid and Beauty, the carpet and Abu in Aladdin and the mice in Cinderella).
http://www.youtube.com/huskcharmer