Though Cybertron is destroyed, Primus takes the remaining pieces of the planet and merges it with a nearby planet, building a new Cybertron without destroying the life that already inhabits the planet, so that the future Transformers would not be unfamiliar with organic lifeforms.
Though Cybertron is destroyed, Primus takes the remaining pieces of the planet to forge a new hollow metal sphere. Primus choose this planet so that the future Transformers would not be unfamiliar with organic lifeforms.