Prophesy says that Twilight Sparkle will not outlive her friends. To preserve the Princess, her friends must survive. They may not be immortal - but one year can become a thousand at the speed of light.
Cryogenics was a pretty cool concept until we forgot about it and buried it. So sorry you're going to be woken up ten thousand years in the future... Give or take a few thousand.
Lyra is convinced that Ruby Pinch and Berry Punch are undercover supervillains, and she will do whatever it takes to expose the truth before it is too late.
A British soilder from WWI wakes up in Equestria, turns into a pony and trys to find a way back home. Within his journal entries, he finds out how Equestria really came to be.