In my main next gen, I’ve decided that the mane six eventually lose touch with the elements when they’re older, Twilight’s friends become friendship diplomats of friendship, helping her run the kingdom and assisting with royal duties, they don’t have time to fight off evil or do the friendship map missions anymore, so their children inherit the elements.  
This was found out when the mane 6 discovered they could no longer use their rainbow power when they attempted to help Luna’s son, Forgotten Whispers, when he was posessed by a very powerful, evil spirit. They visited the Tree of Harmony to try to look for an explanation, and discovered that a small piece of each element had broken off, Celestia determined this meant the tree had chosen new bearers  
So the mane 6 desperately tried to discover who the new Elements of Harmony were, and eventually it was found out that they were one of each of their own children. When the element fragments were given to their new owners, they grew silver chains to wear them. The new elements then saved Forgotten Whispers, harmony was restored, blah blah blah.  
The new Elements do the same things the old elements used to do, they go on adventures to save equestria, fight monsters, and do friendship map missions  
The element fragments are kept in Twilights castle, so the new elements of harmony can use them whenever nessisary
 
From left to right:
 
The daughter of Applejack and Silver Shill, Ambrosia Apple, the new element of Honesty
 
The son of Fluttershy, Discord, and Tree Hugger, Starstruck, the new element of Magic
 
The daughter of Pinkie Pie and Cheese Sandwich, Minty Chip, the new element of Generosity
 
The son of Rainbow Dash and Prince Blueblood, Prince Goldrush, the new element of Laughter
 
The daughter of Princess Twilight Sparkle and Princess Celestia, Princess Wanderlust, the new element of Kindness
 
The daughter of Rarity and Rover, Tequila Sunrise, the new element of Loyalty