1. Sauron gets the ring, conquers middle earth; his minions are given kingdoms
(ie witch-king in Lorien, 2nd Nazgul in Rivendell, etc), but some elves escape
via the Grey Havens and sail to Aman, roust the Valar out of their slumber and,
a la the first age, they have a 2nd War of Wrath (as you suggested). This, to
me, seems the most likely scenario if Sauron regained the ring. I really don't
think it would be "the end."
2. Gandalf leads Frodo and Sam over the same route Gollum takes them, using
more and more of his powers to protect them. Then, as Frodo cannot put the ring
in the fire himself, Gandalf either, somehow, "breaks his mind" to force him to
do it, or, in a heart-rending choice, destroys Frodo and the ring by putting
them both in the volcano somehow.
You know, this idea seemd a lot more intriguing BEFORE I posted
it!
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"Reports of my death are greatly exaggerated"
--Gandalf--
