Due to their origins in medieval fantasy, the idea of dragons living in today's world has been, and remains, a largely unexplored idea. But that was the core premise of Reign of Fire, telling the tale of just how the world would fare if dragons were suddenly released upon it.
The film claimed the world would fare quite poorly, with a majority of the population and nearly all major population centers burned to the ground, serving as food for the flying beasts. The film also added a twist: all dragons were the children (and mates) of a single male.
To end the dragon race, only one, then, would have to be slain. But the male dragon proved that for those who feel the creatures should be feared, not befriended, there's no better evidence than Reign of Fire's monsters.