I would be inclined to believe that kids have been a big part of their discussions already for the simple reason being that they already have some. Harry with his kids at Sentebale and Meghan with her kids in Africa and other places in the world where she's met and been involved with them.
Harry always has been a natural with kids and from what we've heard, really loves to interact with his niece and nephew. The time that made me laugh was when the Obamas visited W&K and Harry, George piped up saying "How come Uncle Harry is so quiet?"
I do think, from what we do know from sources, that both Harry and Meghan want a family and truth be told, should they have them, those will be some very well loved kids.