I believe that Gaidal Cain may come back as Rands child. His disappearance more closely coincides with Rand and Avi's "romantic interlude", than with Olver's age. This impies that Avi is pregnant of coarse. (I am writing this off the top of my head so I do not have quotes or locations to refer you to.) However, we know that Avi had to stay near Rand because of what she saw in Rhuidean. Now consider this. The Wise ones did not make Avi stay with Rand all the time, after a couple of weeks/ months? had passed since their trip. I think they made her wait until the were sure she was pregnant. The Wise Ones would not let Egwene listen to them talking to Avi, but I seem to remeber getting the gist that Avi had completed whatever she had to do. She is also getting all maternal over Olver.