I'm not completely sold on this. I think that it very well may be possible for Dragons to reproduce. Or at the very least, are not limited. Here are my thoughts:
The book linked is written by Torhal Bjorik. What is known of this author? He appears to be a scholar & probably one of the most knowledgeable sources on Dragons & their origins. He has written 3 books on the subject of Dragons. In all of this books he is referring in past tense. Piecing together what credible evidence & accounts he could find on the subject from history. He admits that there is no credible story of how Dragons came to be. Is it possible that it is because no one has ever been able to locate a "lair" in which dragons were produced?
Take Skuldafn, The Forgotten Vale, Aetherium Forge etc for example. Remote areas that are largely inaccessible that haven't been seen in thousands of years by anyone. Is it not possible that Dragons "may" have bred in this remote unreachable areas? Its unknown.
Perhaps they do not breed in the manner in which we normally associate with breeding. What if Dragons enter the world via Akatosh/ a portal or some other method? Stranger things have happened. Take the Soul Cairne, or Soverngarde, or Hircene's Hunting Grounds for example. Otherworldly places of mystery. If Alduin can enter Soverngarde, whos to say other Dragons can not travel between other planes of existence?
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