Does anyone else find it interesting that there is no mention of the Taint on either half of the power in Aviendha's visions? This seems like a huge giveaway by Brandon - I would have thought that the obvious conclusion to TG would be to use both powers to Seal away the DO for good, but then also cut off human access to both powers to prevent the taint from causing another breaking.

But it looks like there's either a different way to seal the Bore.

One other possibility is that in Aviendha's vision, Rand did not seal the Bore properly. This allowed both sides of the power to go unTainted, but let the DO slip through enough to influence the Seanchan takeover. It's possible that he could have driven the Seanchan conquest (though I think they have enough motive regardless).