Nene may have purchased the house alone in order to leave it to her two sons. If it were in both their names, it would then be split between the two boys as well as Greg's kids. We have no idea what Greg's retirement situation is. He might have a pension that is plenty for what he needs.
As for the 'road' show with Kim, I love the idea and I'm not a Kim fan by any means. I think they are both in good places so that they will get along well even if they aren't as close as they once were.