[Tuor in Gondolin]

Smaug was a much too interesting, and fun, character,
to have gotten rid of so early. I believe Tolkien originally
didn't finish the story for his children but just improvised
an ending, but a rewrite to feature more of Smaug, perhaps
involving him in the Battle of Five (Six!) Armies would have
been interesting. Had Tolkien known he was going
to write as such LOTR it might have been interesting to
have Smaug flee rather then be killed to reappear
later ala Gollum. And was Laketown A. S. (after Smaug)
a limited monarchy? Gondor had an apparently advisory
+ council.