It still might just be the first 6 movies and then they'll transition to something different. I'm not saying those link sare BS or anything and I've nevers aid they WILL shift the focus, however those quotes appear to be taken from old info or the writers speculating. My point is that a lot of people think we'll see Luke son and/or daughter as the main character, an this would take away from the Hero story/journey structure that has always been a part of star wars. I think its likely they'll want to keep those elements intact since they've been there for all 6 parts, which means we probably won't simply see Lukes kid as his apprentice etc.... It removes the starting point of the heroes journey. Having a new character not be related to Luke, who Luke discovers is one way they can continue that story structure. Remember, once upon a time Owen was susposed to be Obi-wans brother. However Lucas changed things when he decided to make the Jedi more monk like in their approach to family. Obi-wan wouldn't know his brother. A lot of the comments about Lukes children are old quotes (and one of the more "recent" ones he said he didn't invision LUke being married) so Lucas may simply not see the story the same way today as he did in 1983. Lucas may now invision Luke as being more monk like and not having children.