Well, I am not sure if this has ever been posted, but here is my idea about cleansing the taint. It all goes back to FoH or thereabouts when Egwene has a dream about Rand stepping on, and breaking all of the Cuellendar seals. It occurred to me: what is the link between Saidin and the Dark one? The seals! Fel reiterates this theory when he speaks of clearing up the rubble, the rubble being the brolen seals. Perhaps Cadsuane and/or Rand will realize that breaking the seals will cleanse Saidin without releasing Shaitan like is always assumed. I see this as a very Jordanesque plot twist.