This looks like exactly the lines the fellows at Unhosted [1] have been thinking along. They're working with the remoteStorage protocol [2].

If you're interested in this notion of decoupling storage from apps, I encourage you to check these out. Dare I hope that app.net is planning to work with this community?

  [1] https://unhosted.org/
  [2] http://remotestorage.io/