@Peter

Something that would help this discussion for all is confirmation that RJ did indeed write the scene of Rand exiting the mountain and encountering the old woman that talks to him. His answer on twitter seems to indicate that but there seems to be more and more information about the epilogue coming out every couple days and some of it seems to contradict previous statements. 

She's nothing but a piece of intrigue placed in the books for the fans to be intrigued about. This is made clear by three things.

 

1. Her existence was not something RJ plotted for this book but something based on something Brandon found 'deep in the notes'. Which leads us to two.

2. Brandon has disavowed using the notes--rather, when he needs something, he goes and asks Maria, who does the research.

3. She didn't really do anything. Or rather, she did nothing that wouldn't have occurred just as easily without her presence.

 

Brandon needed something (a mystery for the fans, perhaps--one may note his likening of Nakomi's role to the fandom with Asmodean's), went to Maria who provided him with something he could use, and ultimately the entire thing had little to no plot relevance.

According to yesterday's twitter chat, the scene that includes Nakomi in AMOL was written by RJ: 

http://twitter.com/BrandSanderson/status/294203184098967552

 

Mike Cox ‏@Mikecox20 


@BrandSanderson would like to know how much of the last chapter was written by RJ and how much did you do? #TorChat 



 

Brandon Sanderson

Verified

‏@BrandSanderson

@Mikecox20 I did Perrin and some of the in-between writing with Loial. RJ did Mat, Rand, scene exiting the mountain, and others. #torchat

So that seems to say that RJ did "plot" her for this book.