What will keep determining the success of POB are the curators and the authors and that is why good contents are key and also been able to discover those good contents and curate them is also important,that is why a good "tag" system needs to be created to ensure visibility of contents and prevent good contents from getting hidden...
It is a long road ahead. Things are looking good so far. With a few key developments and creators and curators continuation of their good work... it should be great!