"'They shall not be recovered, I foretell, by any power of the Eldar; and the
world shall be broken in battles that are to come, ere they are wrested from
Morgoth.'"
In other words, they shall be recovered by the Valar, eventually, either
through Beren and Luthien, or through the War of Wrath. But like most
prophets, Melian does not spell out what she means, and Thingol does not
understand the full import, and draws the wrong conclusions (we are on our own,
the Valar have deserted us, we might as well grudgingly ally with the Noldor,
including the sons of Feanor, who at least hate Morgoth). Perhaps Melian
herself does not see the full
picture.
“I dislike Allegory - the conscious and intentional allegory - yet any attempt to explain the purport of myth or fairytale must use allegorical language. (And, of course, the more 'life' a story has the more readily will it be susceptible of allegorical interpretations: while the better a deliberate allegory is made the more nearly will it be acceptable just as a story.)” (From Tolkien Letter # 131.)
Tips for posting in the Reading Room.