1. Romeo and Juliet faked their deaths.
    They did this because they are spies working for the Italian government, and have finished their mission. We then see them embark on a sexy new mission.
  2. Romeo and Juliet come back as sexy vampires.
  3. Romeo and Juliet come back as zombies.
    Not sexy YA zombies, but gross Walking Dead zombies, and they turn Verona into a sick ass wasteland where Benvolio must go against his peaceful tendencies to hunt his zombie cousin.