OR, ponies age much much much slower then humans and
C An stay in stasis for years, hey it's AN answer.
Well since we are on endings, I really think that once it does, in the far far far future end, the last episode should show the Mane 6 moving on, each getting their own life, Twilight back to Canterlot for the next stage after graduating from being Celestia's student, RD to join the Wonderbolt's, Rarity off to a big city after hitting it big as a fashion designer like she always wanted, etc...
But also showing, that they still make time to all get together, and they all still love each other, ending the series on the lesson, that even if your lives take different paths, and you may become separated from those you care for, the bond of true friendship can never be broken, your friends will be there for you, no matter how many miles away they are.
Build a fool proof system, and the world will create a better fool.
My random thoughts