We know that a weave can be tied off to last forever (or as long as the One Power drives the Wheel), but we've also seen weaves specifically made to last forever start to fail due to the Dark One's touch. The main example would be wards against Shadowspawn and vermin that are placed throughout the Tower. It is clear from prior books that though the weaves were inspected, they were set in such a way that they were never supposed to fade. Yet the Dark One's touch causes them to weaken.

I am not quite convinced that saidin and saidar can accomplish the defeat of the Dark One because the Dark One has It's own power source that seems to be the equal of both to use against them. Plus it's own nature can disrupt the One Power, and I have seen no evidence that Linking and using saidin & saidar creates weaves the Dark One can't touch.

Plus, one of the possibilities that RJ indicated in a Q&A was that if both saidin and saidar were used together at the Sealing, both would (or might) have been tainted, which would have destroyed the Wheel itself. It was actually fortuitous that events panned out the way they did because the plan that seemed most dangerous to the Dark One was Latra's, and the procession of events left the tools she had created to be used for the reversal of the Dark One's counterstroke against saidin. Overall, it seems that the Dark One was delayed in a way that indicates using the One Power to solve this problem would be a of disaster - it was a problem that was created with both halves of the One Power drilling a hole past the Pattern, but it seems to require a human rather than mystical solution.

I think the key lies in Rand's t'a'veren connection to Mat, Egwene, Nynaeve, Perrin, Elayne and other people.

Basically, I think he needs to direct his friends in the same way that Ishamael orders around the Forsaken as Nae'blis.