But only a man Travels that way, not a woman - and we know that women were involved. The only similarity to the Bore and a gateway was that you picked up words like 'drill' etc. that are common terms for male Travelling.

And of course, most logically, if it had been a gateway it would be easy to seal him up again. We've seen how Elayne alone can unravel a gateway even if it causes a huge explosion. Even if the Bore 'gateway' had been very complex, they could have somehow unravelled it, or allowed it to collapse on its self.

And even worse, and what actually disproves the gateway theory, is that the Bore is not where it was drilled. If it was a gateway, it would be over the remains of the city of M'Jinn where they created it. As it is, the Bore settled over an area that used to be an island used as a holiday destination.

No, I think what happened was akin to the Dark One being in a balloon for a prison. When a pin pricked the balloon, it caused the entire fabric to rip and the balloon to explode. The Dark One and his power then stuck to the Pattern and influenced it, much like the flattened area of a popped balloon just lying around. Verin even says that the Shadow now lies over the Pattern and influences its destiny. Of course, there is an area where it's very thin where the DO can still engage with the world, but this is merely coincidence due to the nature of the prison and the pattern having strong and weak points, and this being the weak point of both.

To seal it Rand needs to use saidin and saidar to create a perfect physical patch, and use the three ta'veren in combination to bend the Pattern around it and seal it off perfectly. He then needs to use the True Power through Moridin to fend off the Dark One's backblast (Lews Therin alludes to the fact that something MUST touch the DO), which this time won't be able to taint both powers - thus fulfilling how the three will be one, which is doubly linked to Callandor. Callandor is flawed, and magnifies the taint, but not saidin or saidar. I believe this to be a sign that Callandor can draw almost unlimited amounts of the True Power through it - enough to actually repel a direct attack by the DO. The effort will kill Rand, and Alivia will help him die only by being linked to him, but Moridin will be the one to take the final plunge, and Rand will live on in his body - though no longer as a person of fame, but a guy who sails off with his three ladies in a boat.