So, like the rest of you, I've been thinking of the last book and the closure of the series. I've have some thoughts regarding the main plot, the Light' champion vs the Dark One, and the implications. Especially the choice of Brandon Sanderson as a writer got me thinking, with his previous work on the Mistborn trilogy.
I've seen quite a few theories of the nature of the Dark One and the Creator. I agree with the conclusions made by many, supported by statements from RJ and revelations in the books; namely that the Dark One and the Creator are the personifications of destruction (entropy) and it's opposite, creation. Balanced, and equal, they must be evenly matched, and I suppose one can not exist without the other.
My theory is that the world and the pattern where our characters were created by the Creator, complete with a shield protecting his creation from the Dark One's influence. This is regarded as the Dark One's prison, in fact, it is really just a device that keeps him at bay from Randland. Since said entities (The Dark One and the Creator) are equal forces, the Dark One would not be able to penetrate it, "the immovable object meets the unstoppable force", acheiving a stalemate.
This resembles Brandon Sandersons universe in the Mistborn series: Here there was an ancient deal between a power of creation and a power of destruction, that together created the world and it's human inhabitants. The power of destruction was supposed to be allowed to wreak havoc in this world at a later time, but the "Creator" broke the deal, and sealed the destructive force from the world, at great expense to itself. Inevtiably the shield weakens, the dark forces come into play, and a struggle ensues. It is revealed in the last book, that their "child" humanity, through a Mistborn, is able to destroy the chaos avatar since she "inhereted" destructive capabilities from "the Dark One" through his involment in the creation of humanity. This was impossible for the "Creator", since "she" did not have any destructive capabilies and was evenly matched in any case, and thus a human wielding a combination of both powers was the only option to ensure the world's continued survival.
To revert back to Randland, in this Universe the Dark One can only gain entry to the world through the help of an outside force, namely humans and their use of the One Power. The humans in the Age of Legends thus tipped the balance, creating a hole in the Creator's shield, and allowing the Dark One to interfer more directly. It is stated that the One Power drives the wheel and the pattern, so this force must have been derived from the Creator, but humanity are granted access to it, and they are given free will to use it. Also as a tool of destruction that may serve the Dark One's interests... I regard the True Power as a force similar to the One Power, yet derived from the Dark One alone, his essence if you will.
The Creator must have forseen this as an inevitable possibilty, and created a failsafe mechanism in the Pattern to deal with this, aka The Light's Champion. He is able to correct the imbalance through his own free will and choice, yet he might also willingly or unwillingly help the Dark One. He is connected to the land and the rest of humanity in an unique way, revealed through the changes seen during his "dark" and "light" period. It may appear that he bends reality and shapes the world around him...but, I think it is more correct to view it like he negates the Dark One's touch. Examplified, the food decay and missing crops are effects imposed by the Dark One, all Rand does is negating this. He also states that his presence should "keep him at Bay for a short time", before he leaves an area. This is further supported by the realization he has come to; "I was never meant to be a weapon". Indeed...he is no sword...he is simply a shield, or more correct, he seems to be a focus point for the shield that keeps the Dark One at bay. He is the only one who has this ability in the whole world, and it is an ability set in place by the Creator to be able to mend holes in the shield protecting the world. This also explains the silvery light that now protects him from the taint, this is his abilty acting up on himself after he embraced the Light at Dragonmount. (Indeed, he probably wasn't finally chosen as a champion before that point)
In the Age of Legends, he botched the resealing process by creating the seals. Instead, he was meant to use his unique ability as a shield focus point, negate and draw back the Dark One's touch through the Bore (which must happen at Shayol Gul, where it is felt the strongest) and allow the shield to mend itself. He is supposed to be "the flame that keeps the dark maw at bay". (Don't ask me for how long) If the seals are not broken, they will act as a rotten cork in the "bubble", keeping the Bore open despite him being there and negating the Dark One's touch.
Now, this doesn't explain why the Dark One couldn't just off him early on in the series. It might be that the shield (as I regard as a bubble) might mend itself somehow, like an "auto-reset", unless someone from inside Randland stops it from happening. Since the Dark One contemplated (and succeeded in a mirror world) wiping out humanity as a whole, and still wasn't able to break free, I guess we have some support for this. That might also explain how he could turn to the Dark One earlier and serve him,(stated by Ishamael) yet the Dark One still remained sealed. The results from a "reset" rather than a closure through Rand as a negator in the Bore are probably a lot more negative for humanity as a whole, or Rand wouldn't have a role to play. The prophecies also state that "all that he is" can be seized at the moment when he attempts to seal the Bore, and I think the key to the Dark One's final break-out lies here, he seems to have tried every other option, if you refer back to Ishamael's little "chess" game. A half-victory where he is able to sustain lasting damages on humanity, upping his odds for the next tun of the wheel where he might be able to break loose, seems to be in his calculations, evident by his orders to kill Rand when he tried to cleanse the taint. (Before that, he had made sure nobody tried to kill him) It was preferrable to have the taint as an asset for a later attempt, than going all the way to Shayol Gul with the current Rand.
In the end, I agree with Ishamaels philosophy, if the Wheel repeats itself again and again, and the Dark One has a chance, however slight, of getting out, he will make it eventually.
Again, I compare with Brandon's earlier works, in Mistborn. There is a new force at play in the world, seemingly an opposite yet similar force of destruction, that seems to negate the effects of the Dark One. He is stated to be a unique occurence, never seen before. (Rand's wounds, the cleansing of the Taint) namely Padan Fain. This mirrors the destructive capabilities inherent in humanity, given birth by the "Dark One" of the Mistborn series. Maybe this is a potential for ending the cycle, if Padan Fain somehow connects with the DO, locking these two destructive forces in an eternal combat, (or less likely, wiping each other out), essentially leaving Randland alone. This might even break the Wheel, creating a new and linear timeline. Thus we really have a "Last Battle" at hand, not just the end of and age and a new Bore/resealing ages later. If Ishamael should realize this, we might see him returning to the Light, and playing a key role, very fitting with the general theme of redemption in the series.
Maybe RJ or someone saw the philosphical similarities between his and Sandersons plot early on, add his writing capabilities and reverence for RJ, and you would have the perfect person to finish the series. He might also fill in holes left by RJ with his own, similar thoughts...
Well, this make any sence to you?