Yeah, Gorou or Yonebayashi are the ones who will take over. Honestly, I don't think they'll ever quite reach the level of Miyazaki Hayao, but they certainly aren't bad.
With a lot of luck, Takahata may even pop out one more film, too. Kaguya-hime was superb, so I really hope so. But then again, he's even older than Miyazaki, so who knows.