Similar to what pill Cosby said, but with the Vex. Everything's a historical simulation hidden in Vex coding, like a book on a library shelf. Outside the simulation, the Vex have won. They were able to bring their powers of time outside of the Vault successfully. Atheon, The Templar, Gorgons, Oracles, etc now walk the Solar System. What was the last City is now rubble, Vex temples being built over the ruins. The Traveler still stands, but Atheon (with the help of the Templar,) has harnessed its powers of Light, and is bending them to his will, thus creating the simulation we call "Destiny." He is studying Guardian behavior in order to learn how to properly defeat them, should they rise again. In the end, our defeat is inevitable.