Given what seems to be an inevitable mass famine, it seems probable that the Song will be found after all. While in the Dream World, Egwene uses need to find out what she needs to 'preserve the people, and the world, in the face of TG' and it leads her to the conclave of Tuatha'an.

Not only this, but Rand also seems to want to leave something behind for the world to survive. In one of the Fourth Age Prophecies:

And it came to pass in those days, as it had come before and would come again, that the Dark lay heavy on the land and weighed down the hearts of men, and the green things failed, and hope died. And men cried out to the Creator, saying, O Light of the Heavens, Light of the World, let the Promised One be born of the mountain, according to the prophecies, as he was in ages past and will be in ages to come. Let the Prince of the Morning sing to the land that green things will grow and the valleys give forth lambs. Let the arm of the Lord of the Dawn shelter us from the Dark, and the great sword of justice defend us. Let the Dragon ride again on the winds of time.

Note the italicised part. IMO, this plan needs the Ogier on board (with Loial as one of a small numbers that can sing wood).

The discovery of ancient Aiel singing almost seems inevitable. One source from which the actual song may come from is the ter'angreal cache that Elayne holds in Caemlyn. The Library terangreal may be of use here.

Any other ideas to add? Are you as surprised as I am at the liklihood of the Song turning up?