Before his death, Jordan spoke openly of his plans for additional Wheel of Time novels outside of the main story of Rand & Co. These included two more prequel novels and an "outrigger" trilogy set after the Last Battle. Will we ever see these novels?
Probably not. Harriet owns the rights to the characters and the setting now. Her permission would be needed to do anything more with the series. Both Harriet and Brandon have expressed reluctance to continue publishing novels after A Memory of Light.
A lot of people have questions about this, because Robert Jordan had talked about several other books relating to The Wheel Of Time before he passed away – prequel novels, and a trilogy of three books set in the Wheel Of Time world along with several of the characters, but not part of the main continuity, the main story. A lot of people ask about these books, they ask Harriet – Robert Jordan’s widow – but the thing is, we really both feel, Harriet and I, that we don’t want to exploit Robert Jordan’s legacy. To use a metaphor that may be a little obvious, it’s like we’ve been given the One Ring, and we have to let go eventually. The longer we hold on, the harder it will be to let go, and the more we start doing those books, the easier it will be to do reams of stories, and we just don’t want that to happen. I’ve said before that the beauty of a piece of art is in its completion, in many ways. If it’s not allowed to be completed, then the beauty of it won’t be able to stand as a monument to what Robert Jordan achieved. So my instinct right now is to say that no, there won’t be any more. If Harriet decides to do those other five books, and really wants to, then I would probably say yes if she asked me. I love the series, I’m passionate about it, but I’ll leave that up to her, and I certainly wouldn’t do anything beyond those. We’ve spoken about it, and I said that we have to be really careful or we’ll start and keep going and going, and that’s her feeling too.
--Brandon Sanderson SciFi Now Interview