So the book does not say he can't have children. I think that he will eventually marry Meera. Whether he becomes king of Westeros or just king of the north, or neither. I do not have an opinion. I will predict Rickon will survive to the end due to his story having a much different trajectory than in the show.

I completely agree with you, but because it is the right way it is the way that won't get done. Maybe an animated version sim to the mature episodes of Clone Wars would be better.