The film Soylent Green, loosely based on Harry Harrison’s novel Make Room! Make Room!, depicts the “basic idea” you describe, but I’m afraid this basic idea is not only oversimplified but highly unlikely.
If our population continues to grow, at some point the biological infrastructure supporting it will collapse, producing widespread and profound environmental changes. If this occurs, the earth will very probably cease to be a habitable place for large mammals (as it once ceased to be a habitable place for dinosaurs), and this includes us; we won’t be able to “continue on our normal course” by eating each other, any more than dinosaurs were able to continue on their normal course by eating each other.
updated: 02 Jun 2002