The basic cosmology of the WoT universe bears significant resemblances to the
Hindu cosmology, with the ages of the world repeating over and over. I think the ending of Jordan's series could really benefit from using one particular Hindu concept: the day and night of Brahma.
You see, THIS time the Dark One would win! But it wouldn't be the end of everything, only the beginning of a dark period comparable to Brahma's night. Rand & co. would be imprisoned somewhere just like the Dark One used to be. Then, after countless ages of trying to get out and failing, Rand & co. would finally succeed in escaping and binding the Dark One in their place, thus starting a new Brahma's day. They would recreate the universe much like it used to be, but better (or alternatively have the Creator do it, if there really is such a supernatural being). Nynaeve wouldn't only get to play a part in healing the death of a person (like everyone has been expecting), but the death of an entire universe. Now, wouldn't that be great?

It would also explain all the god-allusions we have been seeing re: the main characters, such as Perrin's connection to Thor and Mat's to Odin.
"There are no beginnings of endings in the great Wheel. But it was a beginning."