I believe that in the Last Battle, Rand and the Dark Lord will fight until each of them is seriously struggling. Each of them will gather all the Power he can and release it, simultaneously, at the other in the form of massive bolts of Balefire. The result of this release (and possible impact of two columns of Balefire) will effectively reset the Wheel at the Beginning of the next Era. I think this has happened many times, but this will be the last, for the blast will either destroy the Dark Lord or cause him to be more strongly imprisoned. I think Rand will survive, and Lews Therin Telamon, known as The Kinslayer, will finally be allowed to rest.