Recall the Time of No Return[Eng] - page 230

No, when the cacoon bloow up she fly right up to the sky.

im guessing the prophet who said the prophecy was just Rose disguised since "no one saw his/her face", she said the prophecy to the real twilight so that statment of "empress twilight will not outlive her friends" to make the fake one believe in the prophecy when she took twilight's place, so when they show up the fake will imprisson them instead of killing them to save her own skin

Erm... Spike is a dragon, and by standard, dragons can live a very long time (lifespan can go from some centuries to forever depending the vision of the scenarist). So it's normal he still lives after a millenia. Twilight has nothing to do with it. The only way Twilight could keep her friends alive would be by making them alicorns or some deus ex machina like making them the incarnations/spirits of Harmony (like Discord is the spirit of chaos and disharmony).
Maybe it's already the case ? "You will not outlive your friends." I wouldn't be surprised if we learned they still live in the tree of harmony or something like that.