The Elements of Harmony are no longer connected to the Princesses, but instead to the Bearers. Luna is worried that, given the finite lifespans of the ponies, the Elements may be lost in the future. Celestia, on the other hand, has an idea to ensure that the Elements will always be around to protect Equestria.
This story will be posted twice, once under the 'Teen' rating (still dealing with adult themes, but definitely not showing any 'mature' stuff), and again under the 'Mature' rating... and labeled as such. That way, everyone can read what they want without worrying about jumping around. :)