they went through all that trouble, through the beautiful friendships and peace after the war, only to make the dragons disappear in the end? I mean there's a whole series of books, there's no need for them to end it just like that! In the movie, Hiccup is only 20 years old, they can just take it slow and reveal more of their adventures together. If the franchise is successful, why not continue? Make it as many as the Harry Potter series is they can! The franchise would be ruined if the dragons are gonna disappear!