: : I certainly don't think there were any Dragons left. Minor
: : Wyrms maybe. Probably some orcs left hiding in the mountains
: : etc..

: Tolkien decided there were no more great dragons, but there were indeed dragons (what you call "Minor Wyrms", but he made no distinction). Chrysophylax is one of the later dragons, for instance.

: The Orcs would be left, too, and trolls and other evil creatures like the great spiders.

: Healso speculated that the Blue Wizards, Alatar and Palando, may have begun cults of magic, so they might have survived into the Fourth Age.

: I don't believe it was Tolkien's intention to have any other Balrogs remaining. The passage at the end of THE SILMARILLION is incongruous with some other sources.

Where did you find that Dragon?? Anyway, we have to look at the philosophy behind it all (I must have been conditioned more than I thought here at this "learning-factory"). I believe that the way of Middle-earth is that good cannot exist without being balanced and offset by evil, only by constant struggle can the two contrasts survive as contrasts and not fade into a murky zone of grey nothingness- the one we are in today! Thus evil will reappear, as is its nature, perhaps not by a new Melkor or Gorthaur, but still rearise and get vanguished until the day where the only evil left is the evil left in mens souls. This very evil will multiply and corrupt our soules to the extent that Morgoth himself can seep back in.
This is my interpretation, I hope you find it interesting and that you can agree with, at least some of, it.