User blog:(2142)Gen.Reaper/Dragon Extinction in HTTYD3?

Although the HTTYD movie franchise has taken a different approach than the books, it has been made very clear by Cressida Cowell that they're going to share their ending and explain why dragons are "no more" making me believe that something is going to happen in HTTYD3 that will make dragons go extinct or just simply disappear from the HTTYD Universe as much as it saddens me to think about it and assuming that the movie franchise takes place in the past like the books do, it's probably safe to say that something is also going to happen that will make all records and accounts of dragons ever existing disappear and possibly as well as Berk and any records or accounts of it ever existing.

But my main question is, what is going to happen that will lead to dragons going extinct/disappearing? Will it be humans that eventually exteriminate them despite the best efforts of the Hairy Hooligans, natural reasons(rising sea levels, seismic activity, disease, and ETC), or will it be due to something supernatural like the draogn jewel in the books?(The latter of which I strongly doubt since the movie franchise seems to be avoiding introducting supernatural elements like magic). And what happens to all the records and accounts of dragons ever existing in the world(assuming again that the movies take place in the past) along with any remains of them(skeletons, fossils, and ETC). What are your theories?