The Earth will be a peaceful Utopian world without wars, violence, conflicts and taking risks. The ground for this utopia will be procedure of betrization of the human's brain, that neutrializes aggressiveness and stimulates self-preservation instinct. Humanity will avoid risk, i.e. space travel. The world will be safe and comfortable.
Probably, this world will be too comfortable and too safe as it was for the main character - "they have killed the man in man". The part of man's nature is the ability to take risk, initiative, desire to explore and have some adventures. Later Stanislaw Lem said, that the solution proposed for eradication of social evil in the novel was too primitive and superficial. Society is much more complex than that.
Lem, Stanisław. 1980. Return from the stars. New York: Harcourt Brace Jovanovich.