Good article but I don't exactly agree. The way I see it, there are three distinct categories: leading scorer (AKA the first option offensively), the best player on the team and the team's leader.
Due to cir stances, Parker will likely continue to be the team's leading scorer. However, I don't think that translates to him automatically being the best player on the team and I don't think that the Spurs become Parker's team. Even if TD pulls back and plays at 85-90%, he's still clearly the best overall player on the team. And he's still the leader of the squad. Thus, I disagree with the notion that there is a changing of the guard.
Parker is a damn good player but Duncan is still a better player and a healthy Ginobili is also a damn good player. I still see the dynamic of the team as Duncan being the best with Parker and Ginobili falling in as equal parts behind him. Ginobili is arguably better than Parker on a per-minute basis, although it evens out since Parker can play more minutes.
All that said, the great thing about this group is that they all genuinely don't care about this type of stuff. Each member of the Big 3 would sacrifice personal accomplishments if it meant that the team could reach its goals.