Godzilla vs. King Ghidorah

Time-travellers from the 22nd century return to present day Japan to warn the world that Godzilla will soon return, and his rampage will be so great that the country will never recover.
With the help of a non-fiction writer who has accurately guessed the true origin of Godzilla, the people of the future offer to return to the past and prevent Godzilla's birth. However, upon returning to the present they find that Godzilla has been replaced by an even greater threat; The three-headed demon King Ghidorah!
How can the world survive without the King Of The Monsters to face this new terror?