Pau was probably the last skilled big man in the post, of this current generation. Duncan is pretty good, but he doesn't have the array of moves and quality of finish that Pau did. His combination of size and intelligence, despite not having the explosive athleticism of the likes of Shaq or Hakeem, made Pau truly unique in his own right because his post game incorporated much of Hakeem's finesse work, but didn't have Hakeems agility.
Bynum was at the point where his post game was guided by his unmatched length. His footwork was getting there, but he was thinking about it too much, rather than it being second nature to him. Couple that with the fact that he wanted to work on other parts of his game (jumpers), rather than in the post, mostly because the offense was already loaded with Pau and Kobe, that he didn't get the run to learn.
If healthy, Embiid will probably be the next great post big. Since the "highlight" era (MJ, Nique, Shaq, Kobe) of Top 10 dunks etc...dominated US media, I've always felt that the next skilled big man again be international. On the international level, a lot of coaches and teams stress fundamentals still, instead of being hyped for dunking the ball 20 times a game. If you think about it, the last few good big men have been from abroad. Yao, Pau, Dirk, Marc. They may not possess the same physical prowess the US players are known for, but they sure as hell are a lot more dedicated to learning the game.